Allen & Overy (A&O) Italian senior partner Roberto Casati has quit the London giant to join Cleary Gottlieb Steen & Hamilton.

Casati, who merged his legacy firm Brosio Casati e Associati with A&O in 1998, is one of Italy’s most high profile M&A lawyers and joins Cleary next month in a major boost for the New York firm’s Italian law practice.