Addleshaw Goddard and Allen & Overy (A&O) have picked up lead advisory roles on Yorkshire Building Society's merger with Norwich and Peterborough (N&P) Building Society, creating a combined company with three million members and 224 branches.

A&O is advising longstanding client Yorkshire, which is the UK's second largest building society with assets exceeding £30bn. The magic circle firm's team is being led by corporate partner Richard Slynn, assisted by associates Ilan Kotkis and Susannah Gwyn-Thomas.

Addleshaws, meanwhile, is advising N&P, the UK's ninth largest building society with assets of £3.7bn.

The national firm's team is being led by financial services partner Adam Bennett together with corporate finance partner and head of the financial services markets team Ian McIntosh.

Taking into account the latest transaction, Addleshaws has advised on every one of the last 20 building society mergers. The most recent transaction was announced in March 2010 when Stroud & Swindon Building Society agreed to merge with Coventry Building Society, with Addleshaws advising Stroud and Norton Rose acting for Coventry.

The Yorkshire and N&P merger will see the combined business known as Yorkshire Building Society, with the N&P name to be retained as a separate brand within Yorkshire. It is expected to complete in November.

At the end of 2009 Linklaters advised opposite Addleshaws on the merger of Yorkshire and Chelsea building societies. On that deal Linklaters City corporate partner Stephen Blackshaw advised Yorkshire, with A&O understood to have been conflicted out of advising regular client Yorkshire. Addleshaws advised Chelsea.