The allure of working at smaller Am Law 200 firms rather than a 2,500-lawyer global giant has prompted two London-based partners to make lateral moves ahead of a three-way tie-up that would unite SNR Denton, Paris-based Salans, and Canada’s Fraser Milner Casgrain under the Dentons moniker.

The departures include Salans corporate partner Richard Thomas, who has joined Chicago-based Vedder Price, and SNR Denton trade finance partner Geoffrey Wynne, who will launch a London office for Boston-based Sullivan & Worcester. Vedder Price and Sullivan & Worcester announced their new additions Monday.

Thomas, who officially started with 275-lawyer Vedder Price on January 2, says the firm began to recruit him at just the right time last year.

“I decided that the merger was not for me,” Thomas says, explaining that as a lawyer in his mid-50s, the idea of investing extra capital and making sacrifices as the combined entity builds momentum did not appeal to him. “By the time the benefits will start to emerge from the merger, I’ll be on the downward stretch [of my career].” Thomas adds that he believes for Salans, where he worked for 14 years, the combination is “absolutely the right thing” to do if the firm is to grow.

One of Thomas’s key tasks at Vedder—which had gross revenue of $181 million and profits per partner of $725,000 in 2011, according to The American Lawyer‘s most recent Am Law 100 data—involves launching a corporate group in a London office that now has fewer than 10 attorneys. Starting from scratch doesn’t faze Thomas, who says he has undertaken similar assignments twice before: launching a corporate group for what was then shipping firm Sinclair Roche & Temperley in 1988 and later doing the same at Salans.

Thomas, who focuses on M&A matters and helping U.S. corporations establish a presence in the United Kingdom and elsewhere in Europe, says he will be assisted initially by two associates who are coming with him from Salans. “I’ll be continuing to develop my own practice, as well as coming over to the States and mining Vedder’s database and work,” he says. (A Salans representative did not immediately return a request for comment on Thomas’s departure.) The London office is one of four Vedder Price locations. The others are in Chicago, New York, and Washington, D.C.