[2] He played early on with such bands as The Krewsaders, The Second Thoughts (1964–65, with Patrick Campbell-Lyons and Chris Thomas) and The Eccentrics.

Before joining Thunderclap Newman, Keen shared a flat with and worked as a driver for Pete Townshend of The Who[citation needed].

[4] Keen wrote "Something in the Air", his best-known song, for Thunderclap Newman and recorded two solo albums for Track and Island both of which have been released on CD by Esoteric (Cherry Red).

[2] "I Promise You" from the second album was used in the American TV series, The Big C. Keen was later a record producer for The Heartbreakers[2] and Motörhead.

As a writer, apart from "Something in the Air", "Armenia City in the Sky" and "Club of Lights", he wrote songs for The Swinging Blue Jeans ("Something's Coming Along") and Crokodile Tears ("Your Love").