Callum signed his first professional contract with the Cards in the summer of 2021. The young goalkeeper has been with Woking since the age of 10, featuring at a number of age groups before becoming a regular for the club's academy side, playing an integral part in the run to the third round of the FA Youth Cup in late 2020. His efforts included a memorable penalty save in a 3-2 extra time win over Leyton Orient in round one, prior to a third round meeting with Premier League side Brighton & Hove Albion. Ahead of the 2021/22 campaign he featured in a number of pre-season friendlies and was rewarded with a first-team contract in late August. He will act as understudy to first-choice goalkeeper Craig Ross and Mark Smith.