Easily recognisable as an established TV supporting actor, he is perhaps better known for his role as "Lonely", friend and confidante to Edward Woodwards' "Callan". Hunter's popularity in this role grew so great that during later episodes of the series he was afforded starring roles. Hunter appeared in many other British TV dramas and sitcoms during the 1960s & 1970s. He was supposed to play the part of Willie Mackay in The Highlanders but dropped out and was replaced by Andrew Downie. He reprised his role as Uvanov in five of six of the fully dramatised Doctor Who spin-off series Kaldor City.