McManus was born in Hamilton, Lanarkshire, Scotland, on 21 February 1935 and moved to Hillingdon, Uxbridge, in England when he was three years old, until he moved again at the age of sixteen to Australia, where he performed in amateur theatre groups that led him to becoming a professional actor. McManus appeared in the children's TV series Skippy the Bush Kangaroo and had a guest appearance in the long-running Australian police dramaHomicide. McManus also starred in Tim Burstall's feature film 2000 Weeks, which was the first full-length Australian-produced feature made in Australia since Charles Chauvel's Jedda in 1954. McManus also appeared in the American-produced historical dramaAdam's Woman and co-starred with Mick Jagger in the Tony Richardson 1970 film version of the Ned Kelly story, Ned Kelly. McManus returned to the UK in 1971 and was known to a wider audience when he played roles such as Harry Carter in The Brothers, and Sam Wilson, a coal miner in the 1973 TV series Sam. McManus appeared opposite Peter O'Toole in the 1976 TV movie Rogue Male, and starred as a dour Scots police officer, Jack Lambie, in Strangers, a role he reprised as a guest star in the spin-off, Bulman. McManus also had roles in productions at the National Theatre and the Royal Court Theatre. McManus was also a boxer before acting. McManus is not to be confused with the boxer of the same name from Basildon in England. Some of the more notable shows he was in include:
McManus drank heavily and, after several years of declining health, died from an alcohol-related illness. McManus was hospitalised with severe jaundice in May 1994. McManus died of pneumonia, brought on by liver failure, on 6 June 1994 aged 59 in Glasgow, only eight months after the death of his second wife Marion. In the last two years of his life McManus had also lost his mother, his brother and two sisters. McManus was the first person to be posthumously awarded the Lord Provost of Glasgow's Award for Performing Arts. McManus' final Taggart episode was "Prayer for the Dead". McManus was the first Taggart cast member to die, at 59, only to be followed by Iain Anders who died three years later in 1997, aged 64, from a heart attack. After the death of McManus in 1994, his character was given an on-air funeral in the final episode of the series' 11th season, "Black Orchid". In that same episode, the character of Michael Jardine, portrayed by actor James MacPherson, was promoted to Taggart's position of Detective Chief Inspector.
