Having played once for Gloucestershire Under-25s in 1985,[7] McCrum first played for Ireland in June 1990 against the MCC. He then spent two years out of the Ireland side[3] before playing his only first-class match against Scotland in June 1992.[4] This was followed by his List A debut against Durham the same month,[5] and he rounded out 1992 with a match against the MCC, two matches against an England amateur XI and a match against Gloucestershire.[3]
In all matches for Ireland, McCrum scored 567 runs at an average of 25.77 with a top score of 70 against Scotland in 1992,[3] also his highest first-class score.[4] He took 25 wickets at an average of 29.24 with his best bowling performance being 4/16 against Gibraltar in 1994.[3]