John Shadwell made over eighty league appearances for Exeter City in the seasons leading up to the Second World War having joined the club from Manchester City.

After playing for Turton, John joined Manchester City in 1934 where he featured in two league matches during a two-season stay.

Signing for Exeter City in the summer of 1936, John made his debut at Notts County in August 1936 as he went on to make 30 league starts (with a goal against Walsall) during his first term with the club. In the side from the outset in 1937/38, and making the right-half position his own, John appeared in 40 of 42 league matches and added another goal against Bournemouth in April 1938.

Subsequently, during the last full season before the outbreak of war, John appeared in the opening 14 league games before making a final appearance at home to Southend towards the end of December 1938.

Joining the Army in the Second World War, he was a Corporal stationed in Germany in May 1945.