His compositions include "It Must Be Love", which reached number 14 on the UK Singles Chart in 1971 (and was later covered by the band Madness),[1] "Crying Laughing Loving Lying", and "(Something Inside) So Strong"—an anti-apartheid song inspired by a television documentary in which white soldiers in South Africa were filmed shooting at black civilians in the street—which hit number 4 on the UK chart.

Siffre has published essays, the stage and television play Deathwrite and three volumes of poetry: Nigger, Blood on the Page, and Monument.

Siffre came out of self-imposed retirement from music in 1985, when he saw a television film from Apartheid South Africa showing a white soldier shooting at black children.

Multiple parts of Siffre's 1975 track "I Got The..." were sampled in popular hip hop songs in the 1990s, most notably in the 1999 Eminem single "My Name Is".

[7] From the mid-1990s until Lloyd's death in 2013, he and Siffre lived in a ménage à trois with Rudolf van Baardwijk in the village of Cwmdu, near Crickhowell, South Wales.

[18] In 2014, Siffre appeared on the BBC Radio 4 series Great Lives, championing the life of British author Arthur Ransome.

Siffre said that Ransome's Swallows and Amazons books had taught him responsibility for his own actions and also a morality that has influenced and shaped him throughout his life.