Few lawyers in the City can claim to have the ear of senior figures in Government. Charles Randell, a partner at Slaughter and May, has been ever-present since the summer of 2007, advising HM Treasury on its response to the global financial meltdown.

Since the rescue of Northern Rock, Mr Randell has advised the Government on the collapse of the Icelandic banks, the bailout of Bradford & Bingley and the recapitalisation of Royal Bank of Scotland and Lloyds TSB.

For that, the “magic circle” firm has billed the Treasury more than £20 million, it emerged yesterday.

That may sound like a staggering sum, yet lawyers at rival firms expressed surprise that Slaughter and May’s fees for a year and a half of work on such momentous and complex events had not been several times greater. Linklaters, in contrast, has reportedly racked up in excess of £1 million a week in fees for its work on the Lehman Brothers insolvency.

Mr Randell, 50, is one of the top dealmakers at Slaughter and May but was not widely known before the credit crunch. Now he is one of the most influential lawyers in the City – and the subject of considerable envy at other firms.

“The work Charles is doing is the most interesting a corporate lawyer has had in a decade,” a senior M&A lawyer at a rival firm said. “Any one of us would love to be doing what he’s doing.”

The son of a civil servant, Mr Randell is well-liked by colleagues and competitors for his quiet, cerebral manner and self-deprecating sense of humour. Yet he is also described as a workaholic: in addition to advising the Treasury, he has continued to handle regular clients, such as the energy groups Centrica and RWE.

An Oxford graduate, Mr Randell joined Slaughter and May in 1980 and has, like most of the firm’s top partners, spent his career there. He worked in Germany in the early 1990s during the firm’s ill-fated flirtation with international expansion. Slaughter and May now has only one office of any size, in London, where it concentrates on advising governments and big corporations on high-value transactions.

While its larger rivals face plummeting revenues and make severe cutbacks, Slaughter and May is rumoured to be having one of its best years. It does not disclose its financial results, but reportedly earned more than £420 million in fee income last year. Top partners earn in excess of £2 million.

Mr Randell, a keen sailor, who is married with three children, will no doubt be aiming to continue his dazzling run, but he may also be hoping for something else in the near future: a holiday.