He was born in Rochester, Kent, England, the son of a Royal Navy doctor, Ken Senior, from Holywood, County Down, and his wife Connie.
He was selected for the 1966 British Lions tour to Australia and New Zealand where he played in four Tests and in an international victory in Canada.
[4] He undertook postgraduate study in geriatric medicine at Guy's Hospital, which led to him joining London Irish in 1968.
Irish and Lions colleague Stewart McKinney considered him "a wonderful hooker, the best of our day".
[5] On account of being his country's first-choice hooker for over a decade, he was inducted into the Irish Rugby Hall of Fame in 2007.