Moir Lockhead, the veteran chief executive of FirstGroup, is to retire next March after twenty one years in charge of the bus and train group.His replacement will be his current deputy Tim O'Toole, previously the managing director of London Underground and before that president and chief executive of US rail network operator Consolidated Rail.O'Toole joined the FirstGroup board in May 2009 and became chief operating officer and deputy chief executive in June. He will take over the executive management of FirstGroup from November."I firmly believe that timing is everything and with FirstGroup in a strong position to continue its successful development the time is right for me to hand over to an outstanding team led by Tim O'Toole," added Sir Moir, who was knighted in 2008 for services to transport.Chairman Martin Gilbert added, "As chief executive his vision and drive led the transformation of the group from an employee and management buyout of Grampian Regional Transport in 1989, with 500 employees and £15m of revenues, into one of the world's leading transport operators with revenues of over £6bn and more than 130,000 employees."