The UK's leading lawyers have backed this month's merger agreement between Richards Butler and US firm Reed Smith.

More than two thirds (70%) said they believe the tie-up will create a firm that will be 'more than the sum of its parts' according to the latest Legal Week/ EJ Legal big question survey.

Simmons & Simmons litigation partner Philip Vaughan commented: "There will be a renewed impetus. The process of a merger can really push a firm forward. There will be a lot of energy invested to make sure it will work."

However, the panel of more than 100 leading business lawyers was less convinced about the success of transatlantic mergers so far, with 83% saying they have been 'a mixed bag'. A further 14% said they have been generally disappointing, while just 3% said they have exceeded expectations.

Olswang banking partner Moni Mannings observed: "For the success of a merger there are two key areas, which are easy to say, but few firms actually have. First, there needs to be genuinely complementary business practices. Probably not all of the business areas will be enhanced. And second, the people, partners and culture all need to be similar."

When asked which merger has been most successful, the deal between Mayer Brown and Rowe & Maw received the most support, with 46% of the vote.

The Clifford Chance (CC) merger with Rogers & Wells came in second with 23%, while DLA's combination with Piper Rudnick Gray Cary was third with 12%. Dechert's deal with Titmuss Sainer and Jones Day's tie-up with Gouldens both achieved 7% of the vote, while Kirkpatrick & Lockhart's acquisition of Nicholson Graham & Jones secured 5%.

However, when asked which deal had the most potential, CC and DLA Piper were the most popular choices. Thirty-four per cent said CC had the most potential, while 32% cited DLA Piper. The Jones Day Gouldens merger received 12% of the vote, with Mayer Brown taking 11%. Reed Smith's merger with Richards Butler took only 4% of the vote.

SJ Berwin private equity partner Richard Watkins said: "CC and DLA Piper have a massive international presence and have the potential to springboard off that."

Vaughan added: "The rationale for a merger is all about clients. There is no point doing a merger unless it will increase revenue and you need to have offices on both sides of the Atlantic."