You might not recognise Dave Brown in person, but you've probably seen his work – he's the man inside the shaggy Bollo the Gorilla costume in cult TV comedy 'The Mighty Boosh'. 'Tough Crowd' is an exhibition of his portrait photographs of well-known comedians including Harry Hill, Bill Bailey, Noel Fielding and Lee Mack, with the proceeds from the sale of limited-edition prints going to charity AfriKids. Brown stays out of sight in this venture too, behind the camera. But if the face remains in the shadows, the talent is in plain view. As well as encapsulating the resilience required to make it in the comedy business, the exhibition's title refers to the less-than-engaged audiences ('six alcoholics and a comatose dog' is how Brown puts it) every comedian, no matter how successful, will have had the challenge of winning over at some point in their career. It probably won't come as news to anyone that comedy is a serious business. But there's a real freshness to Brown's portraits, which capture the kings and queens of the gag trade with subtlety and remarkable intimacy.