For the last year at least, Boris Johnson has used just about every avenue available to him to publically lobby  for a reduction in the top rate of tax.
Wednesday's Budget was a victory, then -- or was it? In an interview with the Guardian  today, though unapologetic about his support for the new 45p tax band, Johnson refused to take any credit: "I am not the Chancellor".
Post-Budget polls show that 55 per cent of Londoners oppose the tax cut, versus just 35 per cent who support it. Johnson maintains his defence of the lower tax band, reiterating that "London has got to be tax-competitive". So why the reticence on taking credit for it?
The attack line adopted by Ken Livingstone, Johnsons' rival in the London mayoral race, holds some clues. The so-called "granny tax" was the lone measure in the Budget that had not been leaked in advance, and it caused uproar (you can see the almost universally negative front pages here ). Livingstone's team has been quick to link the freeze in pensioner allowance to the cut in the top rate of tax -- a canny move, since 410,000 Londoners are set to lose an average of £83 a year -- a third of the 1.2 million Londoners aged over 60. These older voters traditionally support the Conservatives.
Johnson is nothing if not a consummate politician, and refused to be drawn on the question of the granny tax in his Guardian interview, instead emphasising his commitment to freedom passes, and distancing himself from the Budget entirely:
It may be some aspects of the Budget are not going down very well. I am not convinced that I will be necessarily associated with those measures. It is not my blooming Budget and it is not necessarily one that I would have written. There is plenty we can do in London to help the poorest and the needy.
But can he avoid being associated with the policies of central government? Elsewhere, he is keen to make much of his links -- his campaign material states that he is "the only candidate who can secure a better deal for Londoners from No 10".
Johnson's appeal has always rested on his reputation as a maverick, and the ability that goes with this to pick and choose which policies he gets behind. However, as my colleague Rafael Behr  argued recently, this may be slipping:
Last time around, Boris was the challenger, which suited his self-image as a bit of a maverick, an eccentric, a TV personality and so, crucially, not a typical Tory. Some of that image remains, but the mantle of office has necessarily imposed a degree of discipline on the mayor. He still gets away with more mannered dishevelment than is usual for someone in his position, but there is an extent to which his pre-election persona has been absorbed into a more conventional political identity. Or, to put it in cruder terms, he is becoming more Tory than Boris.
In that context, his association with the City, Big Finance and the incumbent government could do him immense harm if -- as the RBS bonus episode suggests -- there is an appetite for some populist left noises in the campaign.
The latest polls show Johnson regaining his lead over Livingstone -- but can he maintain this as unpopular measures start to bite?