There was a documentary about The Dave Clark Five a decade ago and it was the most psychotic self-promotion I've ever seen. It was all mostly about him. "I saved the surviving episodes of Ready Steady Go!", "I did a West End Musical with Laurence Olivier!", "I was with Freddie Mercury when he died!"
So only Dave Clark gets his full face on the cover. Not surprising. His head is presumably twice the size of the others to accommodate that ego.