It's a cliche to say that intense activity in business, even to the extent of outright turmoil, is good for commercial lawyers. But this week's extraordinary events on Wall Street are a reminder that the reason it's a cliche is because it's true.

Back in the ancient history of Monday morning, some lawyers glancing at the headlines were predicting a very lean winter. Yet by Wednesday morning it looked rather different, with law firms gaining from a frenzy of bid activity and high-end bankruptcy work in the wake of Lehman's shock Chapter 11 filing. This must now rank as the busiest week that leading law firms in London and New York have seen in many a moon.

So while Linklaters was an early beneficiary with a lead role on the UK end of Lehman's insolvency procedure, Clifford Chance's (CC's) US profile has this morning has had booster rockets attached to it, thanks to Barclays' $1.75bn ($1bn) acquisition of core Lehman assets. And with Barclays set to gain around 10,000 US staff from Lehman, CC also has the advantage of seeing one of its key global clients heavily upgrade its New York presence.

Also handy for City firms is the bid mania taking hold in the UK, as Linklaters and Allen & Overy line up respectively on Lloyds TSB's hastily put-together bid for HBOS.

With HSBC seen as a possible bidder either for HBOS or (harder to believe) Morgan Stanley, the level of bids could also open doors to second-choice advisers as the conflicts pile up. There is also the question for Freshfields of whether its role of advising the Bank of England could conflict it out of M&A bids if the Bank's regulatory efforts end up going beyond wholesale liquidity support towards providing a Northern Rock-style debt guarantee.

And there has also been the irony of seeing Lovells' Christopher Grierson, who spent more than a decade pursuing the Bank of England for supposed regulatory failures in the collapse of BCCI, now advising the Financial Services Authority on its position in relation to the Lehman insolvency.

Stateside, there's been little surprise to Sullivan & Cromwell's Rodgin Cohen and Watchtell Lipton Rosen & Katz's Ed Herlihy proving so ubiquitous in the face of a string of precedent-shattering bail-outs and takeovers. Indeed, Herlihy, who also led on JPMorgan's acquisition of Bear Stearns, appears to be rapidly filling the void many argued will be left when Marty Lipton finally steps down.

But in the case of Weil Gotshal & Manges, whose once-unchallenged bankruptcy franchise was felt to have lost some lustre since its Enron heyday, the Lehman mandate will probably be enough on its own to restore that tarnished brand.

And while transactional lawyers have been getting a boost, former Lord Chancellor, Lord Falconer, today making the keynote speech at the Legal Week Litigation Forum, sees a fair wind for litigators, arguing that Lehman's collapse will spark an explosion in big ticket dispute work.

That's not to make light of the threats to law firms. At the rate events are unfolding, a real body blow to business confidence that will badly hit law firms could easily and rapidly move into view. But it is a reminder that, no matter how closely corporate law firms are said to resemble investment banks, there are still fundamental differences between their business models. Where law firms have slavishly followed certain product lines in banking – say in mortgage-backed securities issuance or bulk conveyancing – law firms have come a cropper of late. But, generally, the relationship is far more complex than a case of 'bank sneezes, law firm catches a cold'. That's why law firm revenues have continued growing this year as many banks have plunged into loss.

But however it pans out, legalweek.com and our US counterparts will be bringing you the news as we break it.