On his return to professional boxing after the war, Houlston switched to middleweight and made one unsuccessful attempt at the Welsh title.
He turned professional in 1935, after he controversially lost the Welsh Amateur Boxing Association final on points to local rival, Albert Barnes.
[2] Houlston continued his winning streak into 1936, with victories over Eddie Cullen of Ynysddu and Tommy Davies of Tylorstown, both held at the Market Hall in Caerphilly.
[2] He continued his punishing schedule with another four contests in August, with only a draw against Norman Rees of Abercwmboi spoiling a perfect start to the year.
Houlston finished the year with wins over Joe Thomas and Percy Enoch, before recording a draw with Les Greenaway at the King's Theatre in Cardiff.
With twenty bouts behind him, and just one loss in his opening fight, Houlston was placing himself into contention for a shot at the Wales Welterweight Championship title.
A win over Curly Edwards at Pillgwelly Social Club in Newport in March 1938 set up a title eliminator with Mog Gwilliam of Pencoed.
The fight went the full distance and the referee gave the decision to Houlston, setting up a challenge for the Wales welterweight title, held by Jack Moody of Pontypridd.
Houlston recovered from this loss with a draw and then a winning rematch encounter with Southern area champion Norman Snow.
Having shown that he had the ability to stop the Welsh champion Davies, Houlston set his sights on winning a second Wales title.
After suffering a technical knockout defeat to Alby Hollister in West Ham on 15 February 1949, Houlston decided to retire from boxing.