Sebastian has played for Carmarthen Athletic, Llanelli RFC and Carmarthen Quins.[1][2][3]
Sebastian has represented Wales at under-16 and under-18 level.[4] He was then signed as part of the Scarlets academy programme[5] and made one competitive appearance for the Scarlets against Sale in the LV Cup.[6]
Sebastian has signed a one-year partnership contract with the Glasgow Warriors which ran until May 2016. It was a full-time professional contract that allowed Sebastian to play for Ayr RFC when not on Warriors duty.[7]
On 21 February 2023, it was announced that Sebastian would depart the Scarlets and join Edinburgh for the 2023–24 season.[8]
International career
Born in England , Sebastian is eligible to play for Wales, but also for Scotland through his father, who was born and raised in Edinburgh.[9]
In June 2021, Sebastian was called up to the Scotland squad for the summer internationals against England A, Romania and Georgia.[10] He was called up again for the Autumn internationals following the withdrawal of Rory Sutherland due to injury. He won his first cap by coming on as a second half substitute during the Autumn Internationals in a match against Japan on the 20th Nov 2021.[11]
In 2023 Sebastian was selected in Scotland's 33 player squad for the 2023 Rugby World Cup in France.[12]