how did he begin his early career?
He took the lead in "By the Shortest of Heads", a thriller.
George Formby
In 1915 Formby Sr allowed his son to appear on screen, taking the lead in "By the Shortest of Heads", a thriller directed by Bert Haldane in which Formby played a stable boy who outwits a gang of villains and wins a £10,000 prize when he comes first in a horse race. 
who is george formby? English actor, singer-songwriter and comedian where was he born? 26 May 1904
wiki:19112845
George Formby [SEP] Early life: 1904–1921
The film is now considered lost, with the last-known copy having been destroyed in 1940. Later in 1915, and with the closure of the English racing season because of the First World War, Formby moved to Ireland where he continued as a jockey until November 1918. Later that month he returned to England and raced for Lord Derby at his Newmarket stables. Formby continued as a jockey until 1921, although he never won a race.