William Caddick was born in Wellington on 14th March 1903. A centre-half, he played for Wellington Town before joining Wolverhampton Wanderers in 1920. At the time the club was in the Second Divisions. In the 1921-22 season Wolves finished in 17th place. The following season they finished last and the club was relegated to the Third Division.

Caddick was appointed captain of the club. Wolves won the Third Division North championship in the 1923-24 season. In the 1924-25 season Wolves finished 6th in the 1924-25 season. The following year it was 4th but after slipping to 15th, the club decided to appoint Major Frank Buckley as manager. As Patrick A. Quirke, the author of The Major: The Life and Times of Frank Buckley pointed out: "His experience at both Blackpool and Norwich of acquiring skilled and talented players at little or no cost and then selling them on at a healthy profit was extremely appealing to those concerned with club finances."

After scoring four goals in 147 games, Caddick returned to Wellington Town in 1926.