Professor David Nutt, who chairs the Advisory Council on the Misuse of Drugs, yesterday accused ministers of devaluing and distorting evidence by their decision to move the drug back up to Class B from C last year (see my previous post, Scientists v Politicians: Round 3).

An e-mail sent to the BBC by an official in the Home Office this morning says that "yesterday's coverage may have some serious repercussions for Prof Nutt and his position as chair of the ACMD".

The note goes on to say "discussions are being had (at) a very high level regarding this issue and a decision will be taken early next week."

Professor Nutt knew nothing about the moves to dismiss him when I spoke to him earlier today, but seemed resigned to the possibility. "They are bound to be considering that," he told me, "thinking about the least worst option."

"I think the issue is whether I am straying into the realm of policy," he suggested. "I personally don't think I was."

A source in the Home Office tells me that "the writing is on the wall" for the scientist, although no decision has yet been made.

On last night's Question Time, the former Home Secretary Jacqui Smith was asked about Professor Nutt's view that the process by which she increased the penalties for cannabis possession last year was "highly politicised".

Dimbleby: "You don't have much time for the head of the advisory council..."
Smith: "Frankly, no."
Dimbleby: "Why not?"
Smith: "I think, actually, this foray into policy is not what his job is about. His job is to advise and my job as home secretary was to decide."

If Alan Johnson does sack the professor, there is likely to be a strong reaction from some in the scientific community who may well argue that this is an attempt to silence independent academic discussion.

However, the online Sun columnist Jon Gaunt argues that the expert advisor has overstepped the mark:

"It's perfectly acceptable for Nutt to have these discussions in the cosseted world of academia but it is totally irresponsible for him to pontificate in public and in his position as Drug Tsar. He must be sacked immediately."

Also appearing on Question Time last night, Liberal Democrat MP Lembit Opik, accused Jacqui Smith of bowing to a tabloid agenda when it comes to drugs policy.

"What's the point of paying people to give you expert advice if you then run your government policy through the red tops?"

Professor Nutt waits to hear his fate.

Professor Nutt, who heads the Advisory Council on the Misuse of Drugs, last year reportedly accused the former Home Secretary Jacqui Smith of being "naive" after her decision to reject scientific advice and re-classify cannabis up from class C to B. She said she had decided to "err on the side of caution", having taken account of "public perception" and "policing priorities".

The two locked horns a second time in February this year after the government again rejected the advice of the advisory council. The scientists had proposed that ecstasy be downgraded from class A with the professor suggesting that the drug caused fewer deaths than horse-riding accidents. The home secretary demanded an apology from Professor Nutt, claiming his remarks trivialised the debate.

Now, Professor Nutt has returned to the fray. In a paper published today, he warns that the decision to put cannabis back into class B may lead to more people taking the drug.

"It may be that if you move a drug up a class it has a greater cachet. People think, 'Oh, it's interesting, maybe we should be trying it because it's a class B or a class A rather than a class C.'"

The professor says the evidence that new high-strength cannabis is causing increased cases of psychosis and mental illness is "difficult to interpret", but that the council's research "estimates that, to prevent one episode of schizophrenia, we would need to stop about 5,000 men aged 20 to 25 years from ever using the drug".

Professor Nutt accepts there is a link between cannabis and mental ill-health. He cites research suggesting that "smokers of cannabis are about 2.6 times more likely to have a psychotic-like experience than non-smokers".

But he points out that "you are 20 times more likely to get lung cancer if you smoke tobacco than if you don't." In other words, he says, "(T)here is a relatively small risk for smoking cannabis and psychotic illness compared with quite a substantial risk for smoking tobacco and lung cancer".

Furthermore, the professor points to what he describes as a paradox.

"Schizophrenia seems to be disappearing (from the general population) even though cannabis use has increased markedly in the last 30 years."

"Research," he argues, "consistently and clearly showed that psychosis and schizophrenia are still on the decline. So, even though skunk has been around now for 10 years, there has been no upswing in schizophrenia."

Nevertheless, the government rejected the ACMD's recommendation that cannabis remain at class C saying that it "believes" there is "growing evidence" of a strong causal link between cannabis and schizophrenia.

The refusal to accept the expert views of a council set up to judge the relative harms of different drugs went down badly with the scientific community in general, and Professor Nutt in particular.

Today, he warns of the negative consequences of what he calls, a "highly politicised" process. It risks causing, he suggests, "great damage to the educational message" on drugs.

"If you think that scaring kids will stop them using, you're probably wrong. They are often quite knowledgeable about drugs and the internet has made access to information extremely simple. We have to tell them the truth."

The government view, though, is that they should adopt a precautionary principle. "Where there is... doubt about the potential harm that will be caused, we must err on the side of caution and protect the public," as Jacqui Smith put it last year.

Professor Nutt attacks the 'safety first' approach arguing that "it starts to distort the value of evidence and therefore I think it could, and probably does, devalue evidence".

He recalls the scare about the MMR vaccine. "People were concerned, on the basis of false science, that the triple vaccine might cause brain damage. This led to a reduction in vaccination uptake and now children are getting lung and brain damage from measles," he states. "The precautionary principle with MMR has been clearly shown to be wrong," he continues. "It has harmed more people than it has helped."

The collision between science and politics over cannabis resulted partly from a government belief that voters thought cannabis was becoming more dangerous and wanted tougher action. However, its own consultation painted a different picture.

Among almost 400 responses from individuals, only 12% thought cannabis should be reclassified as class B. Forty-seven per cent suggested no change and 30% wanted it legalised. Among organisations that responded, only police agencies showed a majority in favour of a tougher stance.

Since the consultation reflected the views of a self-selecting group with a particular interest in the debate, the ACMD commissioned a general opinion poll. That found a majority of people (58%) wanted cannabis reclassified upwards BUT only a quarter (24%) thought the penalty for possession should be increased - the only effect of making the drug class B.

Professor Nutt is not arguing that cannabis is safe - far from it. A report from the ACMD, published last year, spells out that "cannabis is a harmful drug" and that "a concerted public health response is required to drastically reduce its use".

However, he is a passionate believer in the importance of scientific evidence to underpin public policy and seems determined to initiate a serious debate about the relative harms associated with illegal and legal drugs.

You may have read Mr Hurd's claims at the weekend that the 2011 census provided evidence that Labour wanted to snoop on people's sleeping arrangements. For the first time, people may be asked to provide details of the number of bedrooms they have as well as the names, sex and birth dates of any overnight guests in their homes.

His statement to the Press Association read thus:

"An increasingly invasive and intrusive Census will erode public support, cost more and result in a less accurate survey. Just because the Government has the legal powers to ask these questions does not give the state the licence to ask anything they want. These bedroom snoopers are yet another sign of how the Labour Government has no respect [for] the privacy of law-abiding citizens."

Now the head of the UKSA, Sir Michael Scholar, has written to Mr Hurd [36Kb PDF]:

The letter goes on to explain that the census questions "have been designed and tested by the Office for National Statistics after extensive consultation, and approved for submission to Parliament by the Board of the UK Statistics Authority."

"It is quite wrong to give the impression that they are initiatives of government Ministers," Sir Michael points out.

I have just spoken to Mr Hurd, who had not seen the letter which was only recently delivered by e-mail. I read its contents to him whereupon the Conservative Shadow Minister for Charities, Social Enterprises and Volunteering told me: "I stand by my remarks and I am not really interested in saying anything more."

I pressed him as to why he had used the phrase "bedroom snoopers" and attributed the questions to the "Labour Government" when the census information is, as Sir Michael Scholar reminds him, "wholly confidential" and not a party political matter. "I have said what I want to say," Mr Hurd replied, ending the conversation.

It is possible that the inclusion of bedrooms and sleeping arrangements in the proposed Census Questions suggested an opportunity to cast the other side as central control freaks.

But "[t]he question about the number of bedrooms is to help local councils establish whether and where accommodation in their areas is overcrowded," in the words of Sir Michael.

"The question about overnight visitors is needed to achieve more accurate estimates of the whole population, by ensuring that people away from home are included in the Census."

I would have thought this is just the kind of key information that Mr Hurd would welcome, given his interest in sustainable communities. His website explains how it was he who initiated the Sustainable Communities Act to "give local people much greater power over the way in which taxpayers' money is spent in their community".

The distribution of funds is, of course, linked to census population data.

Mr Hurd told me he didn't know who Sir Michael Scholar was. In fact, Sir Michael was former Conservative Prime Minister Margaret Thatcher's Private Secretary at the time when Mr Hurd's father - Douglas (now Lord) Hurd - was Home Secretary.

He is now on the case of any politician - from whatever background - who he believes undermines confidence in official statistics.

This is what she said:

"The parties must listen because, one of the things, I am sitting here and every time Jack Straw or somebody or one of the panel says 'Afro-Caribbean', I am cringing."
(The justice minister holds up his hands in apology.)
"Afri-CAN Ca-RIB-bean!" the woman corrects him.

Discussing race in this country is to walk on egg-shells. When even an experienced signed-up multiculturalist like Mr Straw gets caught out, it becomes obvious how difficult it is even to find the language in which to conduct a grown-up debate about it.

When I have talked to ordinary voters about the subject, there is often discomfort over terminology. Some fear that using the word "black" might be construed as evidence of racism, so they opt for an even more contentious term - "coloured" - in the belief that this will soften their argument.

A few months ago, I received an e-mail from a Chinese viewer who told me he had been offended by my use of the word "Asian" when what I really meant was people who hailed from the Indian sub-continent. On another occasion I was taken to task for the phrase "non-white" - a shorthand for all ethnic minorities which was deemed insulting.

People generally don't want to offend and the shifting sands of acceptable racial vocabulary mean that many dare not even step into the territory. It is a dangerous domain - one false move and you are branded a bigot.

Part of the problem has been the absence of formal public debate about race. Mainstream politicians have tended to opt out or dodge the subject, so the boundaries of acceptable discourse are poorly understood - even by our Parliamentarians.

Last night's programme saw all the panellists try to shift the discussion away from the question of race onto less troublesome terrain.

"This is not a race debate, this is a debate about resources," said the Conservative Sayeeda Warsi, adding that she didn't want a BNP-style discourse "about black and brown people". (I suspect few white politicians would ever dare employ the phrase "brown people", incidentally). All are happy to see the discussion shifted onto safer ground.

Nick Griffin used the expression "indigenous British people" to describe the constituency he seeks to represent.

"The whites!" retorted Jack Straw, keen to push the BNP leader into the race debate. "Skin colour's irrelevant, Jack, skin colour's irrelevant," Mr Griffin responded, as anxious as the rest to avoid the elephant traps of a debate about ethnicity.

This is a problem because it is the recent arrival of people from different ethnic backgrounds into predominantly white communities which is the cause of one of the anxieties underlying the programme. It is not the fact that the new arrivals look different; it is that they behave differently. But neighbourhoods are being transformed because people from other cultures are moving in there. Rapid social change is often linked to ethnic change - and people are disturbed by that.

Can we talk about the alteration of Britain's racial make-up without being accused of prejudice or intolerance? It is tricky to find the words in which to conduct the conversation.

Liberal Democrat Chris Huhne told the Question Time audience that in Britain today "one in two of all Afro-Caribbean children under the age of 16 either have a white mother or a white father". Did he mean children of "mixed race" or "mixed heritage" or "dual heritage" - or whatever the acceptable expression is these days?

Here again we have an important and complex issue - the rapid growth in the numbers of children who don't fit into conventional racial or ethnic categories. There is evidence (see, for example, this Home Office paper [55Kb PDF]) that such youngsters perform less well at school, are more likely to abuse drink or drugs, to end up in prison, to face prejudice or discrimination. But, as I discussed here last year, we don't yet have the language to engage with the intricacies of this.

Globalisation has seen the development of what has been called "identity politics". The trouble is that the debate can barely get beyond issues of classification.

"It is genuinely racist, it is extraordinarily racist when you seek to deny the English... you people wouldn't even let us have our name on the census form," Nick Griffin said last night. "That is racism and that is why people are voting British National Party."

Unable to define who or what we are talking about, we are unable to define the debate. "We are the aborigines here," Nick Griffin said last night. "All of us are descended from Africa," responded the playwright Bonnie Greer.

The British people, I think, are broadly tolerant and welcoming. We don't wish to offend or make a scene. That said, there is deep concern about how racial and cultural convergence is altering our way of life, and yet we struggle to find the words to voice those fears.

For those not actively involved, most strikes are simply irritating inconveniences. But when the Royal Mail stops running, I suspect Britain is affected by a sense of loss that goes beyond the morning delivery.

It is a service with origins at the court of Henry VIII but which developed into a symbol of British creativity and confidence in the mid-19th century. What the world now thinks of as the postal service is a brilliant home-grown invention.

In its Victorian infancy, the Royal Mail was wrapped in the symbols of imperial dominance: the monarch's head appeared on a Penny Black but, such was the self-assurance, the name of her realm did not.

At the same time as the stamps, the Royal Mail produced what became known as Mulready stationery, paper and pre-gummed envelopes featuring a munificent Britannia complete with shield and reclining lion. Beneath her outstretched arms, designer William Mulready drew pictures of people around the globe reading their letters. The message was clear: Great Britain had generously bestowed the world with the benefits of a postal service.

Mulready stationery was lampooned into oblivion, but to this day, I think, Britain's relationship with its mail service contains, for better or worse, hints of imperial heritage.

On the Open Democracy website earlier this month, the philosopher and Scottish nationalist Tom Nairn posted an essay on the English postman as symbol of decline.

As he put it:

"The pathetic Anglo-British postman appears doomed to the tragi-comic posture of treading water in the new delta of globalization."

The traditional postman's uniform (you know, like the one Postman Pat wears) was, argues Nairn, "an imperial vestment wearable by archipelago minorities - Scots, Welshmen, Irishmen - as well as by colonies".

Postulating on a world without the Royal Mail, the essay suggests that the "wearer of the old costume has worn it so long it can't imagine abandonment: nudity and disorientation might result -a nation lost rather than liberated".

The Royal Mail is an essentially British institution and there may be some in parts of the United Kingdom who would cheer its demise, but many more are proud of its place in our national heritage.

Yesterday, Christopher Hope wrote an article in the Daily Telegraph in which he said that "Royal Mail, although in theory a business like any other, transcends the world of commerce and is a vital part of our social fabric".

The British pillar box, to my mind, is an object that "transcends the world of commerce". A brilliant fusion of form and function, it is a design so pleasing that tourists come from all over the world to have their picture taken beside one. However, its birth was not without humiliation, it appears.

In 1857, the Committee for Science and Art of the House of Lords designed a very ornate box festooned with Grecian style-decoration. However, in a major oversight, they forgot to include a hole for the letters to go through. Apparently 50 were made before anyone noticed and so local staff had to smash an opening through the cast iron, rather undermining the beauty of the original design.

The Royal Mail was recently nominated as an English icon - its status discussed by a panel of experts at "Icons - A Portrait of England", a project set up with government money.
It didn't get the nod but among the nomination comments was this:

"This is one of the universal icons that everyone in England can identify with. It has that unforgettable sign that everyone recognises, it is the social hub of many villages (during the day) and it rolls into one many things that you associate with England: the pillar box, queuing, etc."

So, on the one hand you have the Royal Mail - a thread in the national tapestry stretching back through empire to the Tudors. On the other you have the Communication Workers Union - a relatively new organisation (created in 1995) but with roots in a trades union movement which took shape at the same time as the development of the Victorian postal service.

Whatever the rights and wrongs of the dispute, there will be many who find the strike triggering moments of wistfulness. Beyond the rows over late-night deal-breaking and plotting, there is a bigger story about the changing constitution and character of our nation.

As we head for the election, there will be some big promises from political parties on how public services will be so much better under them. It is always sensible to take such pledges with a pinch of salt, but I do wonder whether, come the next election, we might need a barrel or two of sodium chloride to hand.

Schools, hospitals and crime tend to dominate election campaigns and manifestos are crammed with pledges guaranteeing high performance and value for money. Voters care about this stuff - and not just because their taxes pay for it.

In the past, we have had popular promises, for instance, to cut waiting times in A&E departments, to bring more offenders to justice and to ensure that all our youngsters leave primary school able to read and count.

How, though, can politicians keep such promises in future? I ask because both Labour and the Conservatives have made another pledge: to reduce the amount of top-down quality control.

National performance targets backed up by inspection has been the traditional mechanism for trying to ensure that when a minister in Whitehall says "jump", public servants all over the country jump in time.

That mechanism will be dismantled to a greater or lesser degree whichever party controls the Commons next year.

David Cameron has said the Conservatives are committed to "cutting right back on all the interference and instructions from central government - the rules and restrictions, the targets and inspections".

Labour too has promised a "shift away from that top-down approach" with fewer targets, although they still believe they "play an important role in service delivery".

The problem with central targets (and the inevitable inspection regime you need to enforce them) is that they can have unintended consequences.

Those examples I gave earlier all proved problematic: some A&E doctors were found to be treating patients who were less sick rather than those in more urgent need in order to hit the waiting-time target; police officers started arresting people for increasingly petty offences to meet their target; teachers were accused of teaching to the test and neglecting other parts of the curriculum to hit theirs. A recent report from the think-tank Demos found other examples:

"When government decreed GPs would see all patients within 48 hours of an appointment, GPs simply refused to book appointments more than two days in advance. Similar examples are available in housing benefit payments, and social housing repair times. The results can be tragic. The waiting time targets at one eye hospital were achieved by cancelling and delaying follow‐ups, and as a result at least 25 people became blind because of perfectly preventable problems."

Instead of improving services, the targets made some things worse.

And, it is also argued, the obsession with counting and measuring has led to a bureaucratic horror in which public service becomes drowned by paperwork.

Today's story of prison governors allegedly moving inmates about ahead of an inspection is another consequence of a regulatory regime that has come to dominate the daily life and prospects of front-line professionals.

But these systems developed for a reason. Government ministers have to stand up and defend the public services that operate in their name. They are ultimately accountable for performance and value for money.

How does a health secretary ensure that patients get a decent experience at the GP's surgery in Pontefract or Padstow? How does a home secretary make sure officers in Shropshire and Sheffield take neighbourhood policing seriously?

Margaret Thatcher tried to do it with what was called "New Public Management", using market-style mechanisms to encourage efficiency and innovation, but backed up with a system of performance management and executive control to try and make it work.

Labour took it further still as investment in public services rocketed. Tony Blair was determined to ensure that public money didn't spill out of the Treasury only to disappear into a public-service black hole.

Now the government accepts there must be "a new relationship of trust in public service professionals and organisations". The Conservatives echo the rhetoric and would go further.

The risk is that if you take away too much of the regulatory infrastructure, you end up with a very patchy service, a postcode lottery where some people have appalling healthcare or crime control or education because, without the rigour of national targets and inspection, services lack scrutiny and focus and quickly become lazy and inefficient.

For the government, it becomes nigh-on impossible to keep those detailed manifesto promises for everyone.

Advocates of "localism" (and all political parties currently claim to be enthusiasts) suggest that you can measure public-service performance by basic results at the centre and trust local professionals on the ground to work out how to achieve good results. It certainly has its advantages - innovation is more likely to flourish; local problems can get a local solution. But I predict we will see lots of stories about those places that fail to perform and some uncomfortable ministers trying to explain why they are not to blame.

What does seem clear is that Britain has passed the high-water mark on central targets and control. The question for individual voters is whether they believe an era of lighter touch regulation will mean better or worse public services for them.