He passed his 11 plus and consequently attended Cambridgeshire High School for Boys, as had future Floyd members Syd Barrett and Roger Waters.

He also worked for the Alan Parsons' rhythm section at Abbey Road Studios with Pete Moss for the Sutherland Brothers and Al Stewart.

He did session work for Elton John,[4] Procol Harum, Andy Gibb, Bridget St. John, Shirley Collins and The Albion Country Band,[5] David Bowie,[4] Mike Oldfield,[6] Gary Brooker,[7] Roger Waters, Eric Clapton,[8] David Byron, Rick Wright, Jonathan Kelly[4] (credited also with flute), Sally Oldfield, Maggie Reilly, China Crisis, Nick Heyward,[4] Pink Floyd[9] and Brian Joseph Friel.

In 1987, David Gilmour invited Renwick to tour with Pink Floyd as a session musician, and recordings from the August 1988 shows were released in the double live album Delicate Sound of Thunder.

[9] Renwick made a live appearance with the Alan Parsons Band in the 1998 Michael Jackson Gala (replacing the original guitarist Ian Bairnson).