Rupert was born in Carmarthenshire, and grew up in the town of Llandeilo. After starting on the trumpet, Rupert switched to the trombone at the age of 12. Much of Rupert's youth was taken up by playing in the various youth music ensembles in Carmarthenshire and west Wales, as well as the Welsh national ensembles.

 In 2006, Rupert moved to London to study at the Royal College of Music with Byron Fulcher. He then completed a masters at the Royal Academy of Music. Since graduating, Rupert has enjoyed a varied freelance career, working with some of the UK's leading orchestras as well as recording for TV and Film. In October 2017, Rupert was delighted to become an Associate Member of the Royal Philharmonic Orchestra. Away from music, Rupert enjoys running and is a keen cricketer.