The rapid expansion of US firms in London during the past five years shows no sign of abating. At the last count, there were well over 150, drawn from a range of cities such as New York, Chicago, Los Angeles, Washington DC, Cleveland and San Francisco.

Despite predictions that many would withdraw at the first sign of trouble, their commitment to London seems as strong as ever. In Legal Week's fourth annual survey of international firms in London, 37 out of the 43 US firms polled said they planned to increase the number of fee earners at their London arms within the next year.

If anything, the expansion has been gaining momentum. In the past few weeks alone, some of Wall Street's top-tier practices have scored notable coups by hiring partners from the UK's so-called 'magic circle' of top City firms.

While some London offices remain little more than an outpost, a growing band have sought to compete head-on with City firms to provide English law advice on high-profile deals. They have diversified from transactional practice areas, such as corporate and banking, into the likes of employment, tax and intellectual property. As a result, they have started to compete for the best lawyers, offering, in many cases, significantly higher salaries in their bid to woo talent.

And, with the expansion of their practices, an increasing number are also now offering training contracts.

So what do US firms offer to would-be solicitors? There are the obvious financial rewards – some offer lawyers a salary of £85,000 on qualification, compared with the benchmark £50,000 for the top City firms, others pay a 'mid-Atlantic' rate, halfway between the two.

But the rewards are not just monetary and not all US firms pay significantly more than the mainstream. Instead, the first thing to realise is that there is a great variety among US firms in their approach, both in terms of the way they operate and the demands they place on their lawyers.

"If I were applying now for a traineeship, I would think about the type of lawyer I would like to be and then find kindred spirits," says Alison Wetherfield, trainee recruitment partner at Chicago-headquartered McDermott Will & Emery. Wetherfield adds that it is important for candidates to join a firm – US or UK – where the partners have established reputations for that practice area.

In this regard, she believes that US firms have an advantage thanks to the smaller number of trainees they take on each year. "To what extent trainees at a large City firm will actually be working alongside the partners with the big reputations is open to doubt," she explains.

Another attraction of working in a US firm is that while the client base is likely to be as good as that of the leading UK firms, the atmosphere of the office will be more entrepreneurial.

"We are still in a growth mode, even in what is a difficult business environment," says James Gubbins, recruitment partner at Weil Gotshal & Manges. "We are still a young office that is looking to take business away from the top City firms. We are looking for anyone who joins us to make an active contribution to the office's development."

There are potential downsides of training at a US firm – not least the fact that some have developed a reputation for a culture of long hours. In a handful of cases this might be merited, but the reality is that in the vast majority of US firms, a trainee is unlikely to have to work any harder than they would have done were they at a top City firm.

So what do US firms look for in their trainees? Excellent academics are a given, particularly for those practices that see themselves taking on the top City firms. But they are also looking for those who are looking for responsibility and who will thrive in a hands-on environment – because of the small intake, there is no place to hide. In this regard, people who have had experience of a career outside law are often attractive to US firms.

"What we look for is something that is a little bit different," says Robert Bata, European managing partner at Altheimer & Gray. "Someone who has done more with their life than just study."

Case Study 1: Training at a US firm

Charles Balmain
White & Case, London

"My route to White & Case in London was circuitous. I obtained an LLB in Law with European Legal Studies from King's College London in 1998 and then moved to Bruges, where I studied for an LLM in European Law at the College d'Europe. This was an ideal springboard from which to obtain a one-year contract working in the Brussels office of White & Case as a staff attorney.

"This provided me with an excellent opportunity to apply the knowledge of EC law that I had recently gained in a practical context. Indeed, during my year in Brussels, I was involved in a wide range of contentious and non-contentious matters, most notably cartel and competition compliance work. The high calibre of the matters on which I worked, coupled with the level of responsibility I was able to assume, convinced me of the merit of applying to White & Case in London for a training contract.

"My first seat was spent in intellectual property. Two matters were particularly memorable during my time there. The first was my role assisting in the early stages of a technical arbitration related to a defence procurement contract. This led me to appreciate the extent to which, as a lawyer, you will be required not only to advise on points of law, but to do so in context by acquiring a detailed understanding of your clients' businesses. The second was my participation in the negotiation of a UK-wide distribution agreement. Here, finding myself in a boardroom across the table from our prospective contracting party constituted my first real experience at the sharp end.

"For my second seat, I went to Paris. As I had previously found when working in Brussels, being an English lawyer in an office abroad provides you with particularly valuable experience. You are required to tackle a wide variety of subjects and areas of law that are likely to extend beyond those which you might normally anticipate within a specific department in London. This, of itself, is invaluable in stretching one's abilities and building your confidence (safe in the knowledge that, if needs be, a call to the right person in London is always an option).

"On to my third seat, banking: big acquisitions, big loans and do not overlook the glamour of calling Australia in the morning and Brazil in the afternoon. That is probably what I enjoy the most – getting on the phone and actually helping to move projects forward and making a tangible impact on deals.

"As for the all-nighters, they are largely a myth. I do not think I am working any harder than I would be at a magic circle firm. While there is no doubt that if a deal needs to be finalised you will work hard to get it done, it certainly is not a sweatshop."

Case Study II: Training ata US firm

Edward Wanambwa
Bryan Cave, London

"I always wanted to work for a US firm. I had a perception that the atmosphere would be more collegiate and that there would probably be more responsibility as a trainee. You are part of a smaller team and there are not as many fee earners above you.

"I went with another associate here to St Louis, the firm's headquarters, to take part in its new associate induction programme. It was a really good experience and confirmed to me why I had joined the firm.

"The thing that I liked about Bryan Cave in London was that, unusually for a US firm, it was full-service and so you are able to do four seats in different areas, including litigation.

"My first seat was in corporate, where I worked on mergers and acquisitions, corporate compliance and a whole range of other areas. In a big City firm, you might spend the whole of that time in one particular area of corporate finance.

"I then spent seven months with the private client group, which is very different to what most trainees at City firms would do. We do predominantly US private client work, tax and estate planning and I got a good understanding of this area.

"My third seat was in employment and the department here does a very broad range of work. I have been involved in litigation, corporate support and immigration matters – again, I would imagine in the big City firms you would spend all your time focused in one area. This was very much a hands-on experience. I will now spend my fourth seat in litigation.

"Bryan Cave is less hierarchical than UK firms and I feel I have got a broader range of experience as a result. I have been involved in every facet of work we do.

"US firms do have a reputation for long hours, but in my experience that has not been the case. I have worked long hours from time to time, but no more than my friends at other City firms have had to do."