Born in London of a Scottish mother and English father, Callum moved to Scotland when he was six years old and went on to attend Larbert High School. He played for Celtic and Hamilton Accies at youth level before leaving Scotland to sign for Tottenham Hotspur. He spent two years at White Hart Lane before returning north of the border to sign for Hearts.

Callum signed his first senior contact with the Jambos in 2012 and then had a very short period on loan at Alloa Athletic, ironically making his debut for the Wasps against Brechin City in November 2012.

Callum made 30 appearances for Hearts before making the switch to Glebe Park at the beginning of the 2014/15 season which, after starting so promisingly, was decimated by injury seeing him out of action from September to March.

Queen of the South offered Callum a return to full time football and after 2 1/2 seasons in Dumfries he returned to Glebe Park in January 2018.