Britain’s former chancellor of the exchequer admitted yesterday that the UK’s controversial supertax on bankers’ bonuses failed to change the sector’s behaviour over pay as “imaginative” financiers devised ways to avoid it.

The 50 per cent tax on bonuses of more than £25,000 ($38,700) was deeply unpopular in the City of London amid complaints that the industry would haemorrhage talent overseas.

Alistair Darling, who introduced the now-expired levy last year amid an outcry over bank pay, said he thought it was unlikely the tax would be reinstated by the current Conservative-led coalition government.

However, he warned the industry that it faced equally unpopular reforms unless it was more sensitive to the public’s concerns over pay and regulation following the worst financial crisis in generations.

“I think it will be a one-off thing because, you know, frankly, the very people you are after here are very good at getting out of these things and . . . will find all sorts of imaginative ways of avoiding it in the future,” Mr Darling said at a conference in London.

His stance was reinforced by the news that Credit Suisse is awarding a one-off bonus to about 400 senior employees in London after slashing its UK bonus pool for 2009 in response to the tax. The new bonus will not be subject to the tax, which expired in April.

Mr Darling said it would be difficult for governments to take “rational decisions” as long as there are public concerns over banks. “You just need to be sensitive. Otherwise I fear it holds the risk that someone is going to do something which, in the cold light of day, a few years down the line, maybe wasn’t such a good idea.”