Career
In May 2013, Slessor qualified for the 2013/2014 and 2014/2015 professional Main Tour as one of four semi-finalists from the first Q School event. Debut season
Slessor"s first wins as a professional were at the qualifying rounds of the 2013 Australian Goldfields Open 5–4 against Jamie Rhys Clarke and 5–2 against Cao Yupeng, before losing 5–2 to Simon Bedford. His debut at the main stage of a ranking event came at the Indian Open by seeing off Kurt Maflin 4–2.
In New Delhi he lost 4–2 to Mark Davis.
Slessor also suffered first round exits at the United Kingdom Championship and Welsh Open 6–2 to Liang Wenbo and 4–1 to Stephen Maguire respectively. He finished his first season on tour ranked world number 112.
2014/2015 season
Slessor automatically played in the opening rounds of the United Kingdom Championship and Welsh Open, where he was knocked out 6–4 by David Gilbert and 4–3 by Jamie Cope. He then raced into a 3–0 lead over Matthew Selt and held on to beat him 5–3 and play in the last 32 of a ranking event for the first time in his career.
Slessor was beaten in the third round of the first event 4–1 by Oliver Brown and was docked three frames in the second round of event two after arriving late and went on to lose 4–1 against Alex Taubman.