Allan started his political advisor role as a researcher for Tony Blair in opposition as shadow home secretary. He then became deputy press secretary for Blair when he became leader of the Labour Party in 1994. From 1997 he was deputy director of communications at 10 Downing Street, reporting to Alastair Campbell.[2]
Between 1998 and 2001, he was director of corporate communications at BSkyB.[4]
Allan founded public relations consultancy Portland in 2001. The Guardian reported that the consultancy launched on the back of a contract from then BSkyB chief executive Tony Ball, who had previously been Allan's boss.[4] In April 2012, Allan was reported to have sold a majority stake in Portland to media marketing company Omnicom, for an estimated £20 million.[3]
Allan served as chair of the Young Foundation between 2012 and 2016.[7][8]