Shaun was capped at flanker by Wales U20s and was a member of the Six Nations Grand Slam-winning side that included Scarlets team-mates Tom Phillips and Dan Jones. He impressed during the British and Irish Cup competition, but injuries restricted his progress in terms of senior rugby. Switched positions to hooker and captained the Scarlets A side in the Celtic Cup. Spent a spell on loan with Nottingham RFC in the English Championship in 2020-21, but enjoyed a breakthrough season in 2021-22, featuring at flanker and hooker for Dwayne Peel's side.