It's a long way from the English legal culture to the American tradition. But the only thing mergers and acquisitions lawyer Adam Signy has to do when he segues from British magic circle firm Clifford Chance LLP to his new job at New York's Simpson Thacher & Bartlett LLP later this summer is move across London from Canary Wharf to Moorgate.

Signy, 52, has been hired to help Simpson Thacher build an English corporate law practice, and although he's moving at a time when Clifford Chance is busy restructuring and expected to downsize its partnership, word among his peers is that Signy was not one of the partners the London firm wanted to lose.

Signy's practice focuses on M&A, particularly public company takeovers and private equity transactions as well as capital markets, and he's built up strong relationships with private equity firms such as Candover Partners Ltd., Apax Partners Worldwide LLP and Blackstone Group LP.

But Signy is not expected to take all his old clients with him to the new employer. His final date of departure from Clifford Chance has not yet been decided, and he was not available for an interview by press time. But sources said this recruitment was not about poaching business for Simpson Thacher, since the American firm has plenty of clients of its own. It was about taking on a high-profile lawyer and making its first big partnership-level hire in the corporate practice in London.

Greg Conway, managing partner at Simpson Thacher's London office, was reluctant to discuss the matter, in spite of having put his name to the press release on Signy's hiring. But in that statement, he was quoted as saying, "Adam's wealth of expertise and excellent reputation will enhance our ability to offer outstanding legal services for our clients."

Signy has spent his entire working life at Clifford Chance. He trained with the firm after studying economics at Britain's University of Sussex, qualified in 1982 and was made a partner in 1987. Among recent deals, he advised Umbrellastream Ltd., a bid vehicle set up by Candover, Goldman Sachs Capital Partners and AlpInvest Partners NV for their £1.81 billion ($2.75 billion) acquisition of oil services company Expro International Group Ltd. in 2008. In the same year he provided counsel to Melrose plc on its £478 million acquisition of U.K. engineering company FKI plc and in 2007 advised Melrose on its sale of McKechnie Aerospace to New York buyout firm JLL Partners Inc. for $855.6 million. Two years before that, he advised Candover on its sale of baggage handler Swissport International Ltd. to Spanish infrastructure services and construction company Grupo Ferrovial SpA, and in 2004 he served as counsel to Blackstone on its £563 million acquisition of nursing home landlord and operator NHP plc.