Thomas (Tommy) Caldwell was born in London in 1886. He played local football before joining Clapton Orient in 1907. After playing in only seven games this speedy left-winger signed for Southend United.

Caldwell joined West Ham United in the summer of 1909. He made his debut against Exeter City on 2nd September, 1909. Caldwell joined a team that included Herbert Ashton, Fred Blackburn, Bob Fairman, Frank Cannon, George Kitchen, Frank Piercy, Tommy Randall, Danny Shea, and George Webb.

He soon became a favourite of the Upton Park fans and made 30 consecutive appearances before getting injured against Millwall. In his first season he scored 8 goals in 35 games. This included a hat-trick against Bristol Rovers.

The following season he only scored 4 goals in 42 cup and league games. He left the club in 1912 and later played for New Brompton and Reading.