He is best known for his role as Private Pike in Dad's Army, a BBC sitcom set during World War II, of which he was the last surviving main cast member.

[3] Lavender's first television appearance was as the lead in a Rediffusion play entitled Half Hour Story: Flowers at my Feet in 1968.

[4] In 1968, aged 22, Lavender was cast as Private Frank Pike, the youngest member and "stupid boy" of the platoon in the BBC sitcom Dad's Army.

This made him a household name and gave him the great advantage of working alongside a number of experienced actors during his formative years, helping him to hone his acting skills.

These included a reunion with surviving cast members in July 2008,[8] and an appearance on BBC1's Jonathan Ross Salutes Dad's Army in August.

[9] Lavender also recorded a special introduction for the 'lost' colour episode of Dad's Army entitled "Room at the Bottom", which was broadcast on 13 December 2008.

[11] Lavender made a cameo appearance as Brigadier Pritchard in the 2016 Dad's Army film, providing a link with the original series.

[17] Lavender also appeared in films and television series, one of which (Mr. Big, 1977) featured him starring alongside Peter Jones and Prunella Scales.

[21] Lavender then appeared in several other television comedy shows during the 1980s, including two episodes of Yes Minister, and a lead role in the short-lived The Hello Goodbye Man (1984).

[22] In 2001 Lavender joined the BBC soap opera EastEnders, playing the role of Derek Harkinson, a gay friend of Pauline Fowler.

[32] In November 2014, Lavender made a cameo appearance in the film remake Dad's Army directed by Oliver Parker, released in February 2016.

[34] On 9 May 2015, Lavender gave a reading at VE Day 70: A Party to Remember in Horse Guards Parade, London that was broadcast live on BBC1.

[35] In 2017, Lavender appeared alongside Rula Lenska, Johnny Ball, Judith Chalmers and Diana Moran in the reality show A Celebrity Taste Of Italy for Channel 5.

[39] Lavender grew up supporting Aston Villa F.C..[40][41] When filming began on Dad's Army, he was allowed to choose Pike's scarf from an array in the BBC wardrobe.