Thomson began his acting career at the age of four, performing in plays with a company called the Goliards while his family holidayed in Devon. At the age of five, he gave his first TV performance in an advert for Frosties.
It was in 1999 that Thomson secured his first major acting role, playing Young Pip in a BBC adaption of Great Expectations. It was through his role on Painted Lady that he was cast in Great Expectations, as the casting director of Painted Lady thought he would be perfect as Pip. The same year, Thomson made his big screen debut as Pinocchio in The New Adventures of Pinocchio.
From 2000 until 2011, Thomson played Michael Harper in the British BBC sitcom My Family. He is the only one out of the Harper children to have appeared in every series as Daniela Denby-Ashe left the series in 2002, later returning in 2004 and Kris Marshall left the series in 2005.
Thomson portrayed Lysander in A Midsummer Night’s Dream and Claudio in Much Ado About Nothing with the British Shakespeare Company on their 2009 tour of the UK, the Republic of Ireland, Norway and the Czech Republic.
On 20 August 2015, Thomson had announced on his Facebook page that he was leaving acting to return to university, and on 15 September the Daily Mirror reported that he was to attend King’s College in London for three years to study for a degree in philosophy, with the aim of becoming a human rights lawyer.Return