Weil Gotshal & Manges' push to widen its band of European private equity clients has scored a boost as the New York firm's London arm picked up its first major instruction for Bridgepoint Capital.

It is understood that a conflict at Bridgepoint regular Travers Smith handed the US firm the deal, the $535m (£302m) bid for environmental consultancy Environmental Resources Management (ERM) from 3i.

The secondary buy-out, which was agreed this week, looks set to be first successful deal Weil Gotshal has closed for the active mid-market buy-out house.

The deal is believed to be the largest ever leveraged buy-out in UK professional services and is one of Bridgepoint's biggest deals.

Bridgepoint normally uses Travers Smith for legal advice,but the UK firm had a conflict of interest as it had already agreed to act for another possible bidder for ERM, thought to be Exponent.

Ex-Travers Smith corporate partner Mark Soundy led the Weil Gotshal team for Bridgepoint with assistance from US partner Michael Brady and associate Ian Shawyer.

The deal will be regarded as a welcome boost for Weil Gotshal, which has made little secret of its drive to broaden its City private equity practice. The practice was historically driven by Hicks Muse Tate & Furst, but the house has been sending much of its work to SJ Berwin since its US and European arms split up in 2004.

Weil Gotshal's practice received a boost when it was appointed to Apax's panel last year and the firm earlier this year picked up its first instruction for Candover on the acquisition of a division of French electronics group Thales.