Jimmy Savile's ability to commit hundreds of serious sexual offences inside public institutions, "hiding in plain sight" as Friday's police and NSPCC report on his crimes puts it, seems almost incredible.
And for his victims, it is indeed credibility which is the issue at the heart of this scandal.
The simple fact that most prisoners come out of jail and reoffend is the government's central justification for dismantling the state-provided probation service in England and Wales. The hard part is putting something else in its place that will work better.
The Justice Secretary Chris Grayling is determined to cut recidivism but he wants to save money at the same time. His answer is, effectively, to privatise probation. All but the highest risk offenders will be managed by non-state providers.
Regular readers will know that this is a festive quiz with a difference - no-one is expected to know any of the answers.
Now in its fifth year, my Boxing Day Puzzler is specifically designed to foil the resident clever-clogs and give hope to those struggling to focus after the indulgence of Christmas Day.
Was 2012 a bad, good or great year? On one hand, awful weather and the rising cost of food and fuel. On the other, a sporting bonanza and a rise in employment.
We anticipated disaster. Jubilympic scale disaster.
Here's my report into the Pollard review which showed there was "chaos and confusion" at the BBC over a shelved report into sexual abuse by Jimmy Savile, but there had been no cover-up, an inquiry has found.
The report dismissed claims the Newsnight probe was dropped to protect tribute shows to the late TV presenter.
Deputy Prime Minister Nick Clegg is calling for a royal commission on drugs, just five days after the prime minister and the home secretary rejected the idea.
On Monday an all-party committee of MPs recommended there should be a fundamental review of Britain's drugs laws, but David Cameron said that was unnecessary.
Here's my report about the 2011 census which shows the number of foreign-born residents in England and Wales has risen by nearly three million since 2001 to 7.5 million people.
That means about one in eight - 13% - of residents were born outside the UK.
What do current news stories about the Leveson report, Starbucks, nursing and the Scouts have in common? They all have an underlying theme - what it means to do one's duty.
As a young cub with the First Glasgow Scouts in the 1960s, I remember feeling a profound sense of solemnity and significance as I saluted and intoned the promise, on my honour, "to do my duty to God and to the Queen".
Government plans to change the way social housing tenants pay their rent, could have serious consequences for some of the poorest people in Britain - and their landlords. So why are they being kept secret from the public?
Government ministers talk a lot about the importance of transparency and openness in the way the state operates. So it is surprising and disappointing that on an issue that affects the lives of hundreds of thousands of the poorest and most vulnerable people in Britain they are being so secretive.
And so the inquest begins. Why were the people of England and Wales so emphatically indifferent to being given the power to elect their police and crime commissioners (PCC)?
There will be arguments about the wisdom of holding an election in November, the lack of information, the fact that many details were only available online, concerns about politicisation of the police, the vast constituencies, the shortage of high-profile candidates and on and on.
An acting director general. An acting head of news. There's a joke going round that there's more acting in BBC management at the moment than in EastEnders.
But there is a serious point. What we are seeing at the moment is not the thorough structural radical overhaul promised by the BBC Trust but emergency measures to try and steady the ship.
Politicians have complained of an ambush, after David Cameron was surprised on ITV's This Morning by a list of people named online as paedophiles. Is our democracy moving into cyberspace, and should we be worried in case the values of the internet prevail?
Facebook and Twitter campaigns, it seems, are replacing the old-fashioned demo or sit-in.
One begins to lose track of how many inquiries and investigations the Jimmy Savile scandal has spawned. Amid the soul-searching that follows such revelations, there are always demands that lessons be learned so nothing like it "can ever happen again".
That, indeed, was the line from the prime minister on Wednesday when he called for a rethink in the way sex abuse cases are dealt with.
To the general public, there may be something almost bizarre about the editor of one of BBC journalism's flagships - Panorama - commissioning an investigation into why the editor of another of BBC journalism's flagships - Newsnight - decommissioned an investigation.
Tonight I heard one correspondent on a rival channel describe it as "corporate cannibalism".
Here's my report on fears of a low tour-out for the first-ever elections for police commissioners. My question to would-be voters: "Are you excited about the PCC vote?"
With less than a month to go before the first ever elections for police commissioners in England and Wales, there is still some concern that poor publicity will lead to a low turnout. They will be elected on 15 November and replace police authorities in each force area in England and Wales, making police directly accountable to voters.
Here's an excerpt of my report for the BBC's Inside Out programme on some of the radical solutions being tested around England to help tackle the elderly care crisis.
With many of us living longer the challenge of providing care for the elderly is becoming a major issue.
When I was a cub reporter on my local newspaper in the late 1970s, I returned from the magistrates court with what I thought was a front page story. A councillor had appeared on charges of sexual assault on young girls, an alleged abuse of power that had left me shocked.
But my disgust turned to outrage when the news editor told me they wouldn't be running the story. "Our readers don't want to hear about that kind of thing," he said. I remember he used the word "paedophilia" - a term I hadn't heard before. Whatever it meant, it was not a subject deemed worthy of space in that evening's paper.
Mark joined his local paper after leaving school, inspired to become a journalist by playing Waddington's Scoop aged 13.
He has won numerous awards for his reporting. Most recently, his writing won a Royal Statistical Society award for excellence and was a finalist in the online journalism awards in San Francisco.
His ambition is to try to chronicle the story of changing Britain, and for Arsenal to win some silverware.
Before becoming BBC News home editor in 2004, Mark was home and social affairs editor at Channel Four News and political editor at Five News.
This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.