He played representative rugby union (RU) for Wales, and at club level for Pontypridd and Cardiff, as a flanker,[1][2] and representative rugby league (RL) for Wales, and at club level for Leeds, as a prop or second-row.
[3][4] Isaac was first selected for Wales in their opening game of the 1933 Home Nations Championship.
Isaac was placed at open-side flanker, opposite the veteran Tom Arthur who was positioned on the blind side.
[6] When Isaac caused the English half-backs to loose the loose maul, Watcyn Thomas heeled the ball back for Wooller, and then Davey to feed Ronnie Boon who scored a Welsh try.
[7] The game ended 7–3, with all the Welsh points scored by Boon, who had also placed a drop goal.