Sebastian is from Cheltenham in Gloucestershire. He graduated with a degree in Acting from the University of Wales Trinity Saint David in Carmarthen, where he started learning Welsh. From here, he went on to work in the theater in various roles on stage and front of house at venues including the Park Theatre and the National Theater in London. He returned to Wales to study for his Master's Degree in Arts Management at the Royal Welsh College of Music and Drama. Following his placement with the College on Operation Julie, Sebastian was very happy to join Theatr na nÓg full time, and to be able to use his Welsh every day.
