"They are the super-elite, the brilliant. Forget Skadden, they're in another class, this is the Praetorian Guard. It is a fantastic faith in intellect. They believe that if you get a group of very bright people together in a room, you will get it done."

Welcome to Sullivan & Cromwell, a firm that, as can be seen from the above comment from one rival partner, is viewed by some as the US' best all-round corporate law firm. But can it be considered the best in the world?

Whatever the deal tables say – and Sullivan recently topped a three-year breakdown of US firms in the European M&A from Mergermarket – doubts remain over how committed this most conservative of Manhattan institutions is to the international market.

Nevertheless, after years of biding its time in the Square Mile, where the firm was prone to unconvincingly feigning indifference while slowly expanding beyond its projects beachhead, Sullivan has been a more visible presence of late. That long-mooted UK corporate hire came with Allen & Overy partner Vanessa Blackmore in 2006 and was followed up in January 2007 with the individualistic but accomplished Tim Emmerson (pictured) from Milbank Tweed Hadley & McCloy.

The hire of Emmerson, who boasted the best non-magic circle CV this side of Mike Francies, was viewed as a natural move, even without his links to Sullivan's most important client, Goldman Sachs. And with the firm's City office reported to be going great guns and the firm this month announcing that long-time head Bill Plapinger is to hand over management of the 16-partner office to Blackmore and US-qualified Robert Schlein, the question is whether a more internationalist mood is taking hold.

Don't hold your breath
The short answer is: yes but very, very slowly. Handing over co-management of its London office sends out a nice signal but it does come 36 years after the firm first set up shop in the UK. This is also a firm that is rightly known for its extreme caution towards foreign expansion, or indeed anything that deviates from the ethos of a classic partnership built around hard-working intellectuals who can turn their hand to most corporate disciplines.

Likewise, the firm's model of staffing deals leanly is not easily suited to expansion in London (and, conversely, very suited to Paris, where the firm has made more consistent progress). Even with six UK-qualified partners in London, many would also argue the firm needs proper support in tax and a finance practice less reliant on capable practitioners focused on projects.

Yet Sullivan still looks at monolithic, magic circle-style expansionism and shudders. This has at times seemed a curious overreaction, as there is a good deal of middle ground between Clifford Chance circa 1999 and sitting on your hands for five years. It has also led the firm to oddly underplay its desire to replicate its model in a more substantive way in London, as if that was somehow uncouth. That ambiguous message is a big part of the reason the firm has struggled to recruit.

Still, whatever reticence the firm struggles to shake off, progress was made several years back under admired US lawyers like George Sampas and Plapinger. The last two years have also seen the firm expand its UK work, including acting for Olivant on its Northern Rock bid. Other quality clients to put work through its London doors include Silverlake Partners, Macquarie, UBS, Diageo and Rio Tinto (where the firm is currently handling antitrust on the BHP Billiton bid).

Sullivan will build on this City growth – slowly. For which the magic circle will be greatly relieved.

More news, deals and comment on Sullivan & Cromwell

Sullivan on the Legal Week Wiki