Slaughter and May partners are anticipating a record year, with partners at the top of the equity on target to hit £2.5m if current conditions prevail - a jump of 79 per cent from last year's figure of £1.4m.
Slaughters sources said at the half-year stage the firm's billings had grown by nearly 30 per cent after an M&A purple patch in the first six months of the year.
Practice partner David Frank said: "It's extremely encouraging. It's been across the board - the finance side is certainly good, as is equity capital markets. But we're only halfway through."
If the increase continues, the firm would gross more than £400m in revenue at the end of the financial year. Slaughters' traditionally low cost base would pass most of this extra revenue straight to the bottom line. Such a performance will surpass the firm's previous record year, 2004-05, when it turned over £290m and when partners at the top of the equity took home £1.2m.
At the end of the last financial year Slaughters continued to grow, but not at the same pace. It turned over £321m, a performance that yielded plateau partners £1.4m. However, last year Linklaters began to close on Slaughters for the position of the City's most profitable firm when it reported that partners at the top of the equity made £1.32m.
One Slaughters partner said: "Cashflow has been incredibly strong. It's been a really good year from the calendar start - it's exceeded internal expectations."
In the past six months Slaughters has acted on a series of major deals. It advised RWE on the £8bn disposal of Thames Water, Associated British Ports on its £2.4bn takeover by a Goldman Sachs-led consortium and Corus on its takeover by Tata Steel.
However, a partner warned that reaching £2.5m was by no means a foregone conclusion, but that a figure of £2m is well within reach.
He added: "It won't necessarily continue at this pace. Cashflow can be fairly volatile and work levels have declined from the frenzied levels earlier this year. The pipeline is not as good as it has been."