Gaffney worked for MTR for 28 years, holding various engineering roles before being appointed chief engineer operations in 1993. He became operations director in 1998 before becoming managing director of the company in 2003. He retired in 2005 and works as an independent engineering consultant to the rail industry.
Brown stepped down as managing director of TfL's London Rail organisation last November to take up an advisory role on London Rail and Crossrail and officially retires from TfL on 31 March. He has had 40 years experience in the rail industry, overseeing the establishment of the London Overground, the refurbishment of the Docklands Light Railway, the extension of the East London Line and the integration of the Croydon Tramlink into TfL.
Crossrail chairman Terry Morgan said: "These two new appointments will bring considerable railways operations experience and help inform future decisions about signalling, timetabling and the integration of Crossrail services with the existing National Rail and Tube networks."