Greg wrote and starred in sitcom Man Down for Channel 4 in 2013. Such was the success of his debut series that a second is due to follow in 2014. After playing infamously psychotic Head of Sixth Form ‘Mr Gilbert’ in The Inbetweeners (Channel 4) and in The Inbetweeners Movie (the highest grossing British comedy of all time) Greg went on to appear in BBC Three’s Cuckoo alongside Andy Samberg and Helen Baxendale, which earned him a BAFTA nomination for Male Performance in a Comedy Programme.
Greg's debut solo stand up show Firing Cheeseballs At A Dog delighted audiences at the Edinburgh Festival 2010 with tales of his childhood and the tribulations of his former teaching career. The show was nominated for the prestigious Foster's Edinburgh Comedy Award which led to a thrice extended sell-out national tour. The DVD of the show was released in November 2011 and was a Top 10 bestseller. Greg has most recently been back on the road with his critically acclaimed new show The Back of My Mum’s Head.
He has appeared on numerous TV shows, including hosting Never Mind The Buzzcocks (BBC Two) and Live At The Apollo (BBC One). He has also made guest appearances on The Royal Variety Show, Room 101 (BBC One), Mock The Week (BBC Two), Let's Dance For Comic Relief and Sport Relief (BBC One), Would I Lie To You? (BBC One), The Graham Norton Show (BBC One), Live At The Apollo (BBC One), Frank Skinner's Opinionated (BBC Two) and 8 Out Of 10 Cats (Channel 4). Greg was team captain on two series of Ask Rhod Gilbert (BBC One) with whom he also appeared on BBC Two's Dangerous Roads.
Greg is one third of the anarchically brilliant sketch act We Are Klang, who performed four sell-out Edinburgh Festival shows and were nominated in 2006 for the Edinburgh Comedy Award. With We Are Klang, Greg wrote and starred in the group's own sitcom series and a one-off comedy entertainment special for BBC Three.