Tattersall was born in Hurstwood in Lancashire, and was educated at Burnley Grammar School. He left home in 1745, apparently because his father had thwarted his ardent desire to join the Jacobite rebels. He had an interest in horses from an early age, and entering the service of Evelyn Pierrepont, 2nd Duke of Kingston-upon-Hull, he soon rose to be his stud-groom.