When he arrived at Leeds there were four other Australians; Arthur Clues, Bob McMaster, Bruce Ryan and Teddy Verrenkamp plus a New Zealander Bert Cook.
He had his best season in 1956–57 when he captained Leeds to a 9–7 victory over Barrow in the Challenge Cup Final at Wembley Stadium, London on Saturday 11 May 1957, in front of a crowd of 76,318,[4] becoming only the second Australian to lead a winning team at Wembley (after Harry Bath captained Warrington to victory in 1949–50).
He was runner-up to teammate Lewis Jones in the Rugby League Press Writers Player of the Year award in 1956–57.
He retired as a Senior Lecturer in Education from the University of Wollongong in 1990 and purchased the Terrace Bookshop in Kiama which he ran for 5 years.
Keith McLellan married Gwen Maston, the sister of Australian Olympic silver medallist and athletics coach, June Ferguson, on 12 November 1951.