Haydock was infamous for being a practical joker, including one instance when he allegedly cut the power cords to the amplifiers being used by the Dave Clark Five on a concert bill shared with the Hollies.

Although considered a good bass guitarist, he was replaced in 1966 by Bernie Calvert, after disputes related to the conduct of the band's managers.

Haydock vehemently denied this when the story emerged in the press, and he also insisted that he only missed some concert and recording dates because he was ill, and that he provided his doctor's notes to the band to prove it.

When Pete Quaife left The Kinks in early 1966, Haydock was offered the chance to replace him, but turned it down as he believed he still had a place in The Hollies.

[6] On 15 March 2010, Haydock along with Calvert and the other fellow Hollies members Allan Clarke, Graham Nash, Tony Hicks, Bobby Elliott, and Terry Sylvester were inducted into the Rock and Roll Hall of Fame.