Observations: Lost recording of John and Yoko's passion for

A lost recording of John Lennon and Yoko Ono celebrating the release of one of the Sixties' most famous "political" prisoners over the phone has come to light, just as he appears at an anniversary concert in London.

Lennon and Ono appeared at the "Free John Now Rally" in Michigan in 1971 – Sinclair had been given a 10-year jail term after he gave two joints to an undercover policeman. Three days later, he was set free when a court ruled that the state's marijuana laws were unconstitutional. "Lennon came into my life like an angel from above and managed to spring me from prison, for which I am forever grateful," says Sinclair.

John Sinclair plays at "A Freedom Rally Celebration in Memory of John Lennon" at O2 Shepherds Bush Empire, London, W12, 14 June. For details and recording, visit www.gigsandtours.com/Tour/john-sinclair-and-howard-marks)