Calvert was born in Pretoria, South Africa and moved with his parents to England when he was two. He attended school in London and Margate. Having finished school he joined the Air Training Corps, where he became a corporal and played the trumpet for the 438 squadron band. He then went on to college in Canterbury. After leaving college, and having been denied his childhood dream of becoming a fighter pilot, he slowly acquainted himself with the UK’s bohemian scene. Calvert began his career in earnest by writing poetry. In 1967 he formed the street theatre group Street Dada Nihilismus.

Calvert suffered from bipolar disorder, which often caused a fractious relationship with his fellow musicians. At one point he was sectioned under the Mental Health Act. Despite his sometimes debilitating mental health, Calvert remained a fiercely creative, driven and multi-talented artist. During periods away from Hawkwind duties, he worked on his solo career; his creative output including albums, stage plays, poetry, and a novel. His first solo album, Captain Lockheed and the Starfighters, was released in 1974. The record is a concept album; an amalgam of music and theatre focused around the Lockheed bribery scandals. In 1975 Calvert won the Capital Radio poetry competition with his poem “Circle Line”. In 1975, musician and producer Brian Eno produced and played on Calvert’s second solo album, Lucky Leif and the Longships, a concept album which looked at the history of the US and the Vikings, who crossed the Atlantic to reach America before Columbus.

Aged 43, Calvert died of a heart attack in 1988 in Ramsgate, England and was buried in Minster Cemetery near Margate. His gravestone is engraved with the line “Love’s not Time’s fool”, from William Shakespeare’s Sonnet 116.