Allen & Overy (A&O) and Linklaters have secured the lead roles advising Italian aerospace giant Finmeccanica and BAE Systems on the £1bn merger of their avionics businesses.

A&O is advising Finmeccanica on the deal after winning the instruction ahead of former A&O Italian managing partner Roberto Casati, who left the firm to join the Italian office of Cleary Gottlieb Steen & Hamilton last year.