1. Dempsie was born in Liverpool in 1987, but grew up in West Bridgford in Nottingham. He received his acting training from the Central Junior Television Workshop, Nottingham.
2. He has been the voice of the Clearasil advertisements in the UK. Dempsie is a keen Nottingham Forest football fan and attends many home and away matches, he appeared on the UK Saturday morning football show Soccer AM wearing a Nottingham Forest football shirt.
3. In November 2008, he appeared in The Moment of Truth, episode 10 of the BBC show Merlin.
4. In 2010 he voiced Steven, a gay teenager from Nottinghamshire in the Radio 4 play Once Upon a Time. As of 2015, he has appeared in the first three of its five seasons and it is unknown if he will come back.
5. He has also appeared in Harry & Paul on BBC Two, appearing as a northerner who was presented as a gift from the character Harry was playing to his daughter.