Any lawyer doubting that Olswang is serious about its diversification push need look no further than its recently-announced US tie-up, which has defied expectations that the London firm would align itself with one of California's corporate technology specialists.

Instead, the surprise choice of Florida-based giant Greenberg Traurig as a formal alliance partner brings the UK firm together with a large and broadly based national practice that is avowedly full service and expansionary in outlook.

Indeed, Olswang chief executive Jonathan Goldstein says that the Bay Area firms in the market simply did not match the UK firm's current breadth of practice, a reflection of five years' investment in its property and mainstream corporate practice.

This is not to say Greenberg has no profile in the technology market.

That would be hard for any 1,400-lawyer firm – Greenberg clients in the sector include IT giant Getronics, games maker Rare and telecoms company Telefonica.

More significantly, Greenberg is also understood to have acted for Microsoft and Yahoo, two Olswang clients.

And with a respectable roster of US clients that Olswang does significant UK work for – Disney, Fox and Bloomberg among them it is understandable the UK firm felt it could benefit from a stronger US platform.

Still, what Olswang is really judging the venture by is its ability to generate new clients, and this will take time to judge.

Greenberg certainly has the size, but sceptics will question the level of international referrals that such firms bring.

And the level of new business will have to be measured against what Olswang will lose from other US firms.

Olswang seems notably keener than its US partner to stipulate that it is able to maintain relationships with other firms.

In comparison, Greenberg is happier to use the rather more emotive word 'exclusive' and talk of future, joint expansion.

What Olswang's move does illustrate is a shift in the dynamics between US firms and London's thriving
mid-tiers.

Once West Coast firms were considered important referral partners for London tech specialists. But the prolonged slump in the sector, and the development of European practices at firms like Morrison & Foerster and Orrick Herrington & Sutcliffe has changed the game.

Consequently, London firms are reassessing their attitudes towards referrals and mergers with large national US firms.

With Olswang moving decisively, attention will now focus on the intentions of rivals like SJ Berwin and Bird & Bird.

Current indications are that the temptation of hooking up with a larger US firm is growing greater by the day.