Educated at Bury Grammar School, Allan spent nine years working in theatre as a stage manager before he began broadcasting on the offshore station Radio 390 in 1966. Ten years later, he joined BBC Radio 2 to present country music programmes until the late 1980s. In 1994, he presented shows on Country 1035 in London, but did not stay long and was a heavy critic of the station's music playlist. By the 1990s, he was presenting country music programmes on Radio 2 again, but was later replaced by Bob Harris. He also presented a show on Melody FM and was heard at weekends on PrimeTime Radio before the station closed down. In 2002, he won an International Broadcaster award from the American Country Music Association.
Allan also works as a country music journalist, having regularly written opinion pages in the magazine Country Music People and presented country music programming for BBC TV, including coverage of the Wembley Country Music Festival.
Allan began freelancing as a network continuity announcer for BBC Television in 1969 and became a staff announcer three years later, remaining with the Corporation's presentation department until 1994. While announcing for BBC1 and BBC2, Allan also announced for BBC World Service Television during the early 1990s. In April 2012, Allan returned to the BBC as the promotions voice for a season of 1970s-themed programming, including a return to his continuity role.
From 1995, he was heard announcing for Carlton Television in London on relief duties, and during the late 1990s and early 2000s, was heard across much of the ITV network as an announcer for overnight programming. Since 2000, he has also worked as an announcer for the British version of The History Channel, working alongside former BBC continuity colleagues David Miles and Charles Nove. He is currently providing continuity for Sky's Military History Channel.