Sebastian trained at the North Wales School of Dance, following which he immediately made his international debut in Disney's Beauty and the Beast at MGM Studios in Orlando, Florida in the USA. On his return to the UK, he made his London debut headlining Been on Broadway in front of a sold-out audience at the Duchess Theatre in the West End. He recently played Eddie in the London première of Russell Labey and Richard Taylor's Whistle Down the Wind.
Sebastian's other credits include Noah Claypole in Lionel Bart's Oliver, Doc and Gladhand in Leonard Bernstein's West Side Story and ensemble roles in both Return to the Forbidden Planet and Me and My Girl. He has also performed in numerous cabaret and concerts including his solo show Make Me a Mormon and the West End's Christmas in New York.