Son of hurling great Seanie, Tomas won a Minor All Ireland medal with his native Cork but then concentrated on Rugby.
Played with the Irish Schools and alongside Denis Fogarty on the Ireland Under 21 2004 World Cup final side beaten by New Zealand in Scotland.
He burst on the scene when preferred to Peter Stringer for the opening Heineken Cup game against Sale Sharks but had to wait until 2008 to become first choice number 9.
He made his international debut on the tour to Argentina and in 2009 was the regular starter on the Grand Slam side.
Selected for the trip to South Africa with the Lions later that year, he was forced to withdraw after sustaining an ankle injury in the Magners League game against the Scarlets at Musgrave Park in the April.