Sims first played with Clapton as a keyboardist during the 461 Ocean Boulevard sessions after being recruited by Carl Radle. Between 1968 and 1974, he had toured the Las Vegas circuit with Jamie Oldaker playing sessions and gigs, as well as backing Bob Seger and J.J. Cale. Sims toured and recorded with Clapton between 1974 and 1979. He can be heard on all of the releases for those years.