At first blush, the results of Legal Week’s annual US firms in London survey appear contradictory. On the one hand, nearly half of the top US firms in London are now open to the idea of a merger. On the other, more firms than ever are taking on trainees and around half now say they have full-service offerings in the capital. The number preparing to launch new departments has also crept up. This suggests a commitment to long-term investment rather than desperation for a tie-up.

Look a little closer, though, and a pattern does emerge. The weak dollar and uncertain US economy have hurt US firms’ buying power in London. A willingness to take on trainees is more of a defensive move than an aggressive long-term plan, if only because hiring senior partners has become that much more difficult. The US firms’ London arms are also coming under increasing pressure from headquarters to deliver, so upping assistant-to-partner leverage makes good business sense.