Blake starred in three series and two subsequent films of the multi-award winning comedy The Inbetweeners. Harrison's other television work includes the BBC Three Comedy Way to Go and Him & Her, Comedy Central's Big Bad World, The Bleak Old Shop of Stuff, and The Bill. Harrison also starred in all three seasons of The Increasingly Poor Decisions of Todd Margaret, created by David Cross.
Harrison's theatre work includes Step 9 of 12 at the Trafalgar Studios, London in 2012 and The Accidental Lives of Memories at the White Bear Theatre.
Harrison's film work includes Keeping Rosy with Maxine Peake and Re-Uniting the Rubins with Timothy Spall; he also starred in Her Eyes Met With Mine, a short film by Slightly Ajar Productions.
In 2014 he played Alfie in the ITV sitcom Edge of Heaven.
Harrison also provided the voice of Scoop in the British and American versions of the 2015 reboot of the British children's TV series Bob the Builder.
|2010||Reuniting the Rubins||Nick|
|2011||The Inbetweeners Movie||Neil Sutherland|
|2014||Queen of Diamonds||Bench Guy||Short film|
|2014||The Inbetweeners 2||Neil Sutherland|
|2016||Dad's Army||Private Pike|
|2008||The Bill||Pete Monks||2 episodes|
|2008–10||The Inbetweeners||Neil Sutherland||18 episodes|
|2010–11||Him & Her||Barney||2 episodes|
|2010–present||The Increasingly Poor Decisions of Todd Margaret||Dave||17 episodes|
|2011||Day of the Match Aka Halftime||Danny||Pilot episode|
|2011–12||White Van Man||Ricky||3 episodes|
|2012||Bleak Old Shop of Stuff||Smalcolm||3 episodes|
|2012||Comedy Showcase||Steve Lawson||Episode: "The Function Room"|
|2012||Them From That Thing||Various roles||2 episodes|
|2013||Way to Go||Scott||6 episodes|
|2013||Big Bad World||Ben Turnbull||8 episodes|
|2014||Edge of Heaven||Alfie||6 episodes|
|2015–present||Bob The Builder||Scoop (voice)|