After school he joined various junior stage groups and toured with fringe theatrical companies, such as Incubus and Lumiere and Son, until late 1976.
At this point he immersed himself in the punk rock scene as lead vocalist with the band Swank (alongside future members of the Lurkers, Chelsea, and Cuddly Toys)[1] until returning to theatre in 1978.
He played PC Dave Litten in the first series of The Bill, but achieved mainstream success only with the role of Ben in the sitcom 2point4 Children (1991–1999).
He played a starring film role as Arthur Hoyle alongside Samantha Janus and Neil Morrissey in the rugby league comedy, Up 'n' Under.
Olsen appeared in two episodes of the 1981 BBC TV series The Day of the Triffids as a street gang leader who later became an armed paramilitary officer.
[citation needed] Olsen was critically acclaimed for a number of his roles in musicals including The Rocky Horror Show, Cut and Thrust, Gorky Brigade, Welcome Home, The Pope's Wedding, Saved Dialogues, Metamorphosis, Serious Money, What the Butler Saw, Way of the World, and Bad Boy Johnny and the Prophets of Doom.