This is nevertheless an episode that Blair could have done without. To have the complex financial affairs of the millionaire Paymaster General splashed across the front pages while you are cutting lone parents benefit, and your ministers are failing to make a very convincing case for doing so, is, on the face of it, about as nightmarish as things can get for a left-of-centre government.
Mr Robinson's colleagues have spent quite a lot of time over the past 24 hours explaining that he has become the subject of a press feeding frenzy. Certainly John Major damaged his government woefully by letting the Murdoch and Black press between them dictate what he did. But the Labour Party cannot escape all the blame for the frenzy; you can't, day after day in Opposition, fight to ensure that the private affairs of public figures are treated as a legitimate matter of public comment, and then complain when exactly the same happens when you are in government.
It has also been particularly unfortunate that Robinson, as the beneficiary of an offshore trust, is a Treasury minister, a big player in a department committed to doing something serious to reduce tax avoidance. If Robinson had been at - say - the Foreign Office, there might not have been such a fuss. It was unwise for the Treasury to put up Robinson, rather than Brown, to announce the Government's decision to transform the regime on tax-free savings. At the very least it is a serious embarrassment, rather as Harriet Harman's choice of a grammar school for her son was an embarrassment; it worries some arty stalwarts, infuriates others; and it exposes the leadership to the charge that it subscribes to the age-old parental principle of "Don't do as I do. Do as I say."
The question is whether it is more than that. Blair has so far taken the firm view that nothing has so far come to light which suggests that it is. The Prime Minister likes Robinson - which isn't surprising because most people who deal with him do. His weekend interviews demonstrate that he isn't exactly a masterful champion of his own cause. But he has a lot of charm.
Robinson is a good minister. Blair, as well as Brown, trusts his judgement on quite a wide range of issues. He was extremely helpful in ensuring a smooth passage for the windfall tax among the utilities. (On the windfall tax he had been a hawk, arguing that the Government could have reasonably taken more out of their profits than they actually did.) John Prescott has welcomed his close co-operation in the Public Finance Initiative. Finally every Labour government - almost always underpowered in its knowledge of business - needs its millionaire businessman. Wilson's was Harold Lever. And every government, of whatever colour, would be the poorer without a brilliant buccaneer or two.
None of these, in themselves, are sufficient reasons for Robinson to stay. There are however, two rather better ones. The first is a paradox: Robinson's continued presence at the Treasury makes curbs on tax avoidance more, rather than less, likely. There is no reason for challenging his publicly expressed view over the weekend that he is personally arguing within the Treasury for further measures which might be to his personal detriment.
But second, even if he wasn't making the case himself, the current fuss has at least ensured that his mere presence is a guarantor of action. This doesn't mean that Gordon Brown isn't deadly serious about fulfilling his Green Budget pledge to tighten up on avoidance. There is no reason why one-off capital sums, as well as regular income, received by British citizens from offshore trusts shouldn't be taxed. But it won't be easy; the law is desperately complex and there are big vested interests to take on here.
To the scams in urgent need of abolition catalogued here yesterday by Polly Toynbee, I would add just one: widespread avoidance of inheritance tax by the rich. "Billions of pounds", said a Labour document before the election, "are held in trusts principally for tax avoidance". Just imagine the bedlam that would greet Brown on Budget Day next March, if with Robinson at his side, he announced that the Government still had no firm plans to start recouping it.
The other is that whatever else Robinson has done, his financial dealings appear to have been irrelevant to his conduct as a minister. One of the reasons why the Opposition is on such weak ground is its own record of protecting politicians - such as Neil Hamilton and, for too long, Jonathan Aitken - whose private conduct was relevant to their political life. By contrast they have not yet been able to show that Robinson's financial affairs have affected his conduct as a minister.
There is an important caveat here. Robinson's explanation has so far been rather like the answer given by Norman Lamont when, more than a decade ago, in very different circumstances, he was pressed to account for his famous black eye: "complicated but innocent". If anything came to light which fatally undermined that, and therefore his fitness to be a minister, Blair has left himself just enough room to demand his resignation. Robinson would certainly have done better to disclose more from the first - about the date of the trust's formation and its subsequent share dealings - than he did when its existence first came to light. His original reticence is one of the reasons why the affair has damaged the image of a very image- conscious government. But on the known information, he has done nothing illegal as a private citizen and nothing improper as a minister. Unless that picture alters Blair is right to keep him.