(2016) Greg played Edward Kynaston in the original theatrical production of 'Nell Gwynn' in London's West End. It won the Olivier for Best New Comedy that year.
(2018) Greg played the lead role of Paul Smith, CEO of Celador and co-creator of Who Wants to Be a Millionaire, in 'Quiz' by James Graham (X+Y; Brexit - An Uncivil War) in London's West End. Nominated for Best New Comedy at the Oliviers 2019.
(2021) Stage play: Playing lead role of Dromio of Ephesus in The Comedy of Errors for the Royal Shakespeare Company.