During 1967, he fought for both the British and European titles, losing to Henry Cooper (Great Britain) and Karl Mildenberger (West Germany) respectively.
During World War II, his father served in the Royal Air Force and the boys lived with their mother in Bedfordshire, and later in Ilford, Essex.
Walker's older brother George had been a successful light heavyweight boxer and persuaded him to enter the sport, with the ambition eventually to turn professional.
Soon after a first-round knockout of 6 ft 4 in (1.93 m) American Cornelius Perry in an international tournament broadcast on national TV, promoters were competing to sign Walker to lucrative contracts.
Billy refused a rematch with Derry heavyweight Jim Monaghan after a disputed first-round TKO in a four-nations competition in Dublin 1961.
With brother George as his manager, Walker embarked on a professional career that in six years would see him challenging for both the British and European titles.
[citation needed] This was during London's "swinging sixties" and Walker took full advantage of his wealth, fame and good looks to have fun[vague] with a series of beautiful women.
[citation needed] Although he never fought in the US, during his career he stopped rated American heavyweights Charlie Powell, Bowie Adams, Ray Patterson and Thad Spencer inside the distance.
In spite of a few weeks' coaching at Harry's Gym in Harlem, Walker's defensive skills remained marginal, and some of his later fights against world class opponents had to be stopped owing to cuts and excessive bleeding from his nose.