He turned professional in May 1960 and went on to score 15 times in 106 games for the Shrimpers before earning a £9,000 move to Crystal Palace in September 1963.
[9] He was signed by Palace as a replacement for Steve Kember who they had sold to Chelsea for £170,000, and he fitted in so well that by November he had been made captain.
However, on 29 December 1972, Kellard moved on to Portsmouth having made 46 appearances in his second spell at Palace, scoring 4 times.
[12] The following January he joined Hereford United on loan, and later in 1975 left to play in South Africa for Durban City F.C., having scored six times in 62 games for Pompey.
He moved to Cape Town City, but returned to England in September 1975, joining Torquay United, but played only twice for Malcolm Musgrove's side, the first being a 7–1 defeat away to Tranmere Rovers and the last against Hartlepool United, before leaving league football to join Chelmsford City.