Born in Market Weighton within the East Riding of Yorkshire, William was the fourth son in a family of thirteen and weighed 14 pounds (6.35 kg) at birth.

[2] His father, a master tailor (Note: Market Weighton parish registers instead say he was a Butcher) measured 5 ft 9 in (1.75 m), while his siblings and mother Anne were of average size, although one sister who died in an accident at age 16 was tall.

[3] Bradley travelled with a group of showmen under the alias of the Yorkshire Giant; at the time, the freak shows were popular and would draw large crowds.

As the tallest British man, Bradley was a prized asset in the business joining the huge Yorkshire Pig which was bred in Sancton two miles from Market Weighton.

[3] He was even presented before King George III at Windsor who gave him a large golden watch on a chain, which he wore for the rest of his life.