SJ Berwin is narrowing its US referral relationships, with Boston private equity shop Goodwin Procter emerging as one of a select group of firms now allied with the City leader.

SJ Berwin has been attempting to cut back the number of firms it uses in the US for some time and said the process was still ongoing – with the firm taking a number of measures to get closer to the firms it works with in the US.

The firm now operates a secondment programme with several of its US allies and has also been involved in joint pitches to clients. Last month it held a joint seminar with New York law firm Paul Weiss Rifkind Wharton & Garrison on the opportunities for listing funds in Europe.

SJ Berwin also has an informal referral relationship with California law firm Cooley Godward Kronish. The UK firm recently advised alongside Cooley when it landed its first-ever finance role on a US buy-out – advising Bank of Scotland on its funding of Lydian Capital Partners' acquisition of Trilogy Health Services last autumn.

Regina Pisa, chairman and managing partner of Goodwin Procter, said: "We share similar practice strengths and the relationship enables us to address our clients' needs in cross-border transactions in those practices. Our relationship is by no means an exclusive one and each firm maintains other similarly-close relationships on a global basis."

SJ Berwin senior partner Jonathan Blake denied that the firm was considering a merger with any of its US allies, saying: "Our strategy is to have a closer relation with a number of US firms, but we have no agenda to merge. Internationally, we are trying to get closer to a number of firms, but we are not talking about exclusive relationships."

As well as in the US, SJ Berwin's strategy has seen it move to strengthen links with a number of firms in China, India and Central and Eastern Europe.