Greg Proops is a bit of a legend. The smart-suited American is a terrific stand-up comedian but may be better known as a master of improvisation. He first made his name in the UK as a regular performer on C4’s Whose Line Is It Anyway? You name it, he can make it funny. Later this month he joins that other great improv institution, The Comedy Store Players – Richard Vranch, Lee Simpson, Andy Smart, Neil Mullarkey and Josie Lawrence – when they play their 20th annual gig at the Globe Theatre.