Windmill was born and educated in the Black Country. Having been born in Brierley Hill he attended Moor Street Council School in the same town. He played initially for Halesowen Town before joining Aston Villa in 1903 and making his debut on 7 November 1903 in a 3–1 home win against Newcastle United. This was his only appearance of the 1903–04 season and he would have to wait until 22 October1904 for his next game. This marked the start of regular league appearances for Windmill and of a successful FA Cup run which saw Aston Villa beat Newcastle United in the 1905 FA Cup Final, on 15 April 1905, with Windmill gaining a winner's medal. In the 1905–06 season his opportunities to play were less and he turned-out in only 16 games. In the following three seasons, however, he made only a single appearance in the league in Aston Villa colours. Windmill, as with many footballers of the time, had employment away from football, in his case teaching. In 1910 the localeducation committee forced him to end his footballing career as they felt that it interfered with his teaching duties.