Increasing pressures to work overtime and a falling number of available partnerships are driving young lawyers to leave their firms, according to a recent survey.

Employees are often moving into banking and other related industries, prompting firms to introduce attractive bonus schemes and additional time off in return for working overtime.

The poll of the top ten law firms, carried out by the Financial Times, found that some are losing up to 20 per cent of their non-partner lawyers a year.

The findings show that lawyer’s rising salaries – up by as much as 20 per cent last year – and a number of schemes have failed to abate the trend. London law firm Simmons & Simmons has introduced so-called “Owl and lark” leave in order to relax. To be granted an hour off a lawyer must complete three hours of unsocial work before 8am or after 9pm.

Firm Clifford Chance gives vouchers for childcare nursery places, Slaughter and May offers well-man and well-woman tests, and Freshfields Bruckhaus Deringer and Linklaters have on-site dentists.

To exasperate the situation, more than a thousand London lawyers took home £1 million or more last year, three times as many as 2006, with the bulk of earnings going to partners.

Last year, for the first time, all five “magic circle” law firms — Clifford Chance, Linklaters, Freshfields Burckhaus Deringer, Allen & Overy and Slaughter and May — had average profits per partner of more than £1 million.

The results show that this elite group enjoyed its second year of revenue growth in double figures, with fees rising 14 per cent annually to reach £10.5 billion. The flow of lawyers leaving for banks could slow as the buy-out market dwindles, and graduate recruitment is expected to remain strong. This could create, for a while at least, a new band of young lawyers with a serious lack of deals to work on.