(1) "He goes against all the unwritten laws of being a rock singer: He's clean cut, he's a nice lad, he looks healthy...Cliff's broken all the rules and he's bigger than anybody. It's amazing." Adam Faith.
(2) "He gets better and better as the years go on. Cliff has class. It is difficult to have show-biz without him!" Olivia Newton-John.
(3) "As I move ever closer to the bus pass and pension book, my thoughts drift back... to the Summer of 1958 in Soho, London. Hank Marvin and I were just 16 years old, and we had just met an older man (he was 17) who was to change our lives..." Bruch Welch.
(4) "After Elvis you had very few people, in fact, I don't know of another act that has had a career as long as Cliff's, with as many hits." Phil (Everly Brothers).
(5) "He's always in what's happening musically and for me that is the key ingredient for his continual success." Elton John.
(6) "He never achieved the same impact in the United States despite several chart singles there, but he has remained a popular music, film, and television personality in the United Kingdom and he retains a following in other countries." Wikipedia.
Reference: Extracts from The Ultimate Cliff by Peter Lewry & Nigel Goodall (1996). Except for # 6.