Thomas studied the clarinet at The Purcell School and the Guildhall School of Music & Drama. After several years as a freelancer working with many of the British orchestras (particularly with the LPO), he spent nine years as a member of the Royal Philharmonic Orchestra before finally joining the LPO in September 2014. He recorded many of the principal clarinet cornerstones of the orchestral repertoire while with the RPO, and Schubert's Shepherd on the Rock for EMI.