But this year has seen the resurgence of several mid-size firms. Rowe & Maw, Dechert, Hammond Suddards Edge and CMS Cameron McKenna have all witnessed bumper first quarters.
For deals involving a European target, CMS Cameron McKenna is the surprise entrant. Last year the firm failed to make a showing in the top 25, but it is now ranked sixth. Its deals include acting for Nomura International on the acquisition of the £150m Cumberland Hotel from Compass.
Rowe & Maw, Dechert and Hammond Suddards Edge have all entered the top 25 M&A rankings. Again, all were absent from the same table (completed deals involving a UK target) last year.
Rowe & Maw's role in Persimmon's £562m takeover of Beazer is key to its fifteenth-place ranking. This year, the firm has completed five deals with UK targets with a total value of $1.8bn (£1.3bn).
National firm Hammond Suddards Edge acted on 19 UK targeted deals with a total value of $1.4bn (£976.7m), giving it a ranking of 17. It advised Jabil Circuit on its £390m acquisition of manufacturing operations from Marconi.
Dechert, formed last year with the merger of Titmuss Sainer Dechert and US firm Dechert Price & Rhoads, acted on three deals. These included advising Travelex Holdings on its £441m acquisition of a Thomas Cook subsidiary.
But while the smaller City players have witnessed strong first quarters, US firms are not faring as well. Sullivan & Cromwell, Skadden Arps Slate Meagher & Flom and Simpson Thacher & Bartlett have all been pushed out of the top-10 firms for completed deals involving a European target, with Simpson Thacher absent from the top 25 altogether.