Career
On 15 August 2011, Hassan joined Conference North side Harrogate Town on a month-long loan deal, where he scored twice from seven league appearances. Hassan made his senior debut for Hartlepool on 14 January 2012 against Exeter City in Football League One, coming on as a substitute for James Brown in the 80th minute. Hassan was released on 10 May 2012
After his release from Hartlepool, Callum went on trial with Huddersfield Town, N ottinghamshire County, Workington and Whitby Town.
He signed for Conference North side Workington in August 2012 on a pay-as-you-play deal after being recommended to Workington boss Darren Edmondson by his former Hartlepool coach Mick Wadsworth.
In September 2012, Hassan moved again to Northern Premier League side Blyth Spartans on a free transfer. He scored his first goal for Blyth in the Field Artillery Trophy first qualifying round in a 4–1 defeat to Witton Albion but left the club in mid October.
Callum then moved to Northern League side Bishop Auckland where he played his game on 2 November in a 4–0 defeat to Spennymoor Town coming on as a half-time substitute. lieutenant was announced via Bishop Auckland"s Twitter account on 26 November that he had been released by the club
In early December 2012 Callum signed for Bishops local Northern League rivals West Auckland.
In 2014, the forward rejoined Harrogate Town and was released in October 2014. In 2015, Hassan began trials with Portsmouth and impressed fans with a brief appearance in a 1-1 draw against neighbours Havant & Waterlooville at Westleigh Park. In October 2015, Hassan joined Kidderminster Harriers on a short term deal and scored on his first start for the club
Callum has gained cult status with local fans due to his unusually strong physique and outstanding work rate.