Power had his West End debut in Bill Kenright's 2005 production of the Tennessee Williams play "The Night of the Iguana" alongside Woody Harrelson. Initially playing Hank, Power then shared the role of Shannon with Harrelson, and the two alternated midweek over the last three months of the run. As part of the centenary productions of Terrence Rattigan in 2011, Power played Mark Walters in In Praise of Love at the Royal & Derngate theatre in Northhampton. In 2015, Power returned to the West End to perform juror 7 with Tom Conti, Robert Vaughn and Jeff Fahey in Bill Kenright's production of "Twelve Angry Men" at the Garrick Theatre.