As WPP returns, will HSBC quit UK?
In a symbolic sense, it matters that Sir Martin Sorrell has decided that the government's corporation tax reforms and cuts are enough to lure his advertising giant back from Dublin to the UK.
The chief executive and founder of WPP told me:
"We've now had a chance to read the small print. It is subject to drafting and enactment of the relevant legislation, and to board and shareowners' approval".
But he confirmed what he told the BBC's Today Programme - which overnight he made up his mind that the Chancellor has done enough to bring the home of WPP back to London (last night on the Ten O'clock News he applauded the reforms, but hadn't yet bought his ticket back from Dublin).
The government cannot contain its delight at WPP's decision - largely because its corporate tax changes are designed to make the UK a better place for multinationals to base themselves.
Those reforms aren't cheap. By the government's own estimates - and critics say they under-estimate the cost - they will lead to around £2bn of lost revenue a year by 2015 (and see my note from yesterday for more on the detail of the reforms to the so-called Controlled Foreign Company Rules, the taxation of multinationals' branches, and cuts in the rate of corporation tax).
For the avoidance of doubt, WPP's intentions don't constitute a trend. It is too early to say whether they will lead to the kind of investment and job creation in the UK by multinationals that the government desires.
And it is unclear whether Sorrell's thinking has been influenced by the economic weakness of Ireland, which may ultimately undermine the new Irish government's ability to maintain low tax arrangements for multinationals that other EU members such as Germany want the Irish to scrap.
All that said, this morning George Osborne has had the kind of advertising from an advertising giant that money can't buy.
Of course, some may say that is because Sir Martin Sorrell is just one of the usual Tory suspects. But I don't think that's quite right: he was on reasonable terms with the last government. That said, he has been a supporter of the government's public spending cuts. And he is a member of David Cameron's business advisory group.
One more thing. There is a reasonable chance that if WPP comes back, like a giant ship in the night it may well pass HSBC - the giant international bank - travelling in the opposite direction.
It is not corporation tax that particularly irks HSBC but George Osborne's new levy on the banks. Emigration from the UK is a very live option, that comes up for discussion at every board meeting, I am reliably told.
The reason for HSBC's itchy feet, as I've mentioned here before, is that it is furious that George Osborne's new bank levy is applied to the money it borrows outside the UK, as well as its domestic liabilities. And that really matters, because HSBC has far more of its assets and liabilities outside the country than inside.
HSBC estimates that it could save itself more than £250m in levy every year by the simple expedient of moving its HQ for tax purposes somewhere else. And HSBC's directors tell me that the bank's shareholders - its owners - tell them that they don't see why HSBC should needlessly pay this tax, so are urging them to move their caravan on.
Now some of you - who don't seem to be fond of banks - might well say "good riddance". But the Treasury tells me it definitely wouldn't want to see HSBC go, though doesn't seem to have a cunning plan to persuade it to stay.
Update 13:25: But to where on earth could HSBC move its home?
A source at the top of the bank told me the group now sees the centre of its world as Africa - in the sense that Asia, Africa and the Middle East are expected to deliver most of the future growth.
So in an ideal world, it might move its domicile to Qatar or Dubai.
But with most of the Gulf either in flames or looking pretty combustible right now, emigrating there at his juncture could look eccentric, to say the least.
Now in spite of rumours to the contrary, my HSBC sources say there is no possibility of the bank returning the legal HQ to Hong Kong.
One of them muttered something about it not being a brilliant idea to sit under the clenched fist of a one-party Communist state. I can't imagine what he means.
On the other hand, HSBC is so big in Hong Kong and mainland China that moving home to the US is thought to be out of the question - because to do so would not go down especially well with the Chinese authorities, for geopolitical reasons (it was that consideration which made it impossible for HSBC to appoint the former Goldman Sachs partner, John Thornton, as chairman).
Now some months ago, I was told Australia was favourite as alternative domicile.
But given the sheer size of HSBC - a balance sheet roughly equivalent to UK GDP - it's not clear that the Australian central bank would quite cut the mustard as lender of last resort for the global giant.
In the end, the magnitude of the UK economy, the potential resources deliverable by British taxpayers (or us), and the size of the Bank of England's balance sheet combine to mean that the UK looks a decent place to be based, given that the credibility of all banks depends on them having access to emergency liquidity in a disaster.
For HSBC, is it worth paying an extra £250m a year in a special levy to the Treasury for the guarantee that the Bank of England and British taxpayers would always bail the bank out, whatever the weather.
HSBC's board might grump about the cost (they do), but that fat fee might represent value for money.