Even as Gillan became a rock god with Deep Purple, he starred in the famous musical's cast album.
The Clapton cover was a big factor in introducing the reggae star to an international audience.
His fourth solo album was a celebration of both Eric's refuelled creativity and some great musical relationships.
Three lucky audiences on Eric Clapton's 1974 tour saw him joined on stage by half of The Who.
The 40th anniversary edition of the Saturday Night Fever soundtrack will be released in expanded commemorative configurations on 17 November 2017.