Sir David was the 684th Lord Mayor of the City of London, serving from 2011-2012. He was Alderman of the City of London representing the Ward of Langbourn from 2005 to 2024 and served as Sheriff of the City in 2009-2010. Sir David was a solicitor, a partner in Allen & Overy LLP, the international law firm, from 1979 to 2015. He is Past Master of the Worshipful Company of Fletchers, the City of London Solicitors Company, the Worshipful Company of Information Technologists and the Worshipful Company of Glaziers. He is Chairman of Northern Ballet, a Trustee of the National Opera Studio, a Steward of Henley Royal Regatta and a member of Leander Club.