The rise of international law firms within the UK legal market continued unabated in 2005, with the top 30 international firms depriving UK rivals of total revenue worth more than £1bn for the second year running. The top 30 international firms in London, which are all headquartered in the US, increased their overall combined turnover by 10 per cent to report a total revenue of more than £1.1bn. Although this was still far shy of the £8.17m of revenue generated by the UK top 30.

All of the top 30 US firms had solid years off the back of the bullish corporate and finance markets. But in certain cases, such as with Debevoise & Plimpton and LeBoeuf Lamb Greene & MacRae, the past 12 months have been little short of astounding.

Debevoise was the biggest success story, reporting a staggering 67.5 per cent increase in UK turnover to reach $56m (£32m). The firm only needed 14 London-based partners to achieve the record jump in revenue, which equates to a little more than 10 per cent of the firm's total revenue of $536m (£306m).

LeBoeuf reported a similarly astounding 43 per cent increase in UK turnover, from $34m (£19.5m) in 2004 to $48.8m (£27.9m) in 2005, and an even more astonishing 67 per cent increase in UK profit per equity partner (PEP), from $681,000 (£389,000) in 2004 to $1.1m (£650,000) in 2005.

LeBoeuf London managing partner Peter Sharp succeeded in keeping the excitement out of his voice when he attributed the increases to "steady growth" across the firm's key practice areas of insurance, reinsurance and energy. "There was no jumbo deal or specific trigger that sparked the growth for us. It's been a broad advance across the range of what we do," he said.

This is a sentiment mirrored by the majority of the international firms and it is sure to send a chill through their UK rivals, which have preferred to believe that their US competitors have made little headway in locally generated mandates. A rather misguided belief, given that Sullivan & Cromwell advised Goldman Sachs, in conjunction with the company's management, on the £410m take-private of UK discount clothing retailer Peacock, and with Dechert acting for Travelex on its £1.6bn sale to Apax Partners.

Transatlantic tie-ups remained a hot topic in 2005-06, although the focus did shift temporarily from US firms looking for UK tie-ups to UK firms looking to expand into the US firms' own hunting ground - namely Freshfields Bruckhaus Deringer's search for a US bedmate.

But it was Reed Smith that stole a march on the international pack, revealing its merger intentions with Richards Butler . But if the integration of the two firms occurs, it may dent Reed Smith's favourable UK performance next year. The US firm's London and Coventry offices outstripped the firm's overall performance for the second consecutive year in 2005, with UK revenue up by 16 per cent, compared with a 12 per cent firmwide increase.

The existing US-UK tie-ups showed improved results in 2005. The merger between Kirkpatrick & Lockhart and London's Nicholson Graham & Jones, which came into effect on 1 January 2005, resulted in the firm entering the rankings for the first time last year. It has since capitalised on the tie-up, increasing UK turnover by 10 per cent to reach $54m (£30.8m) and average UK PEP by 36 per cent to $539,500 (£308,000).

But Mayer Brown Rowe & Maw (MBR&M) remains the undisputed success story of the transatlantic mergers, retaining its second-place ranking with a UK turnover of $145m (£83m). MBR&M is, however, an exception to the rule, as it retains an independent UK presence.

Baker & McKenzie, meanwhile, retains its stronghold at the top of the international table, with UK turnover narrowly breaking the £100m mark. London remains the firm's largest office by headcount and boasted a turnover that was up by 9 per cent to £100.4m.

The profitability of the international firms in London still outstrips their UK rivals'. The top 30 international firms offered an average PEP of £746,200 for the last financial year, compared with just £573,000 for the UK top 30. However, this is down on the international firms' 2004 financial year figure with an average PEP of £789,900, signalling a slight balancing out in the UK market.

However, US firms are still loudly touting around guaranteed pay packets of £1.5m upwards to star partners in the UK and Europe. Such hefty remuneration packages saw yet another swathe of lateral movements to international firms during 2005, although these did not reach the same level as seen in previous years.

Kirkland & Ellis's hire of Linklaters private equity partners Graham White and Raymond McKeeve, along with Weil Gotshal & Manges' hire of Lovells head of private equity Marco Compagnoni spring to mind.

Skadden Arps Slate Meagher & Flom made its intentions clear by bolstering with a string of hires in London. Shearman & Sterling corporate rainmaker Adrian Knight defected to Skadden in November, followed shortly by Allen & Overy finance partner Clive Wells. But Simpson Thacher & Bartlett arguably made the most notable lateral hire of 2005, poaching A&O's legendary leveraged finance partner Tony Keal, ensuring the solidification of the firm's already tight relationship with Kohlberg Kravis Roberts & Co.

Meanwhile, Bingham McCutchen and Gibson Dunn & Crutcher make their debuts into the rankings of the top 30 international firms in London. This is at the expense of Morgan Lewis & Bockius, which reported a UK turnover of £10.3m, and Kilpatrick Stockton following the dramatic downsizing of its London office late last year.