 Thomas, along with Graeme Hick, held the record for highest score in the Twenty20 Cup from 2004 to 2006, after scoring 116 not out to lead Glamorgan to a win with three balls to spare against Somerset Sabres in the group stages of the 2004 tournament.On his County Championship debut in 2000, Thomas made 82 in a drawn match against Essex, described by the BBC reporter as a "dream debut".It was to be his highest score in first class cricket, and he only made two higher scores in any form of the game, the aforementioned Twenty20 century and 93 against a Durham Cricket Board XI in the C&G Trophy.