The Wigmore Hall, with its laboriously marbled and gilded period interior, doesn’t exactly scream “rebellion”. Yet for the second time in as many months its conservative classical crowd saw recital conventions discarded like the too-tight bow tie that they are. Players strolled on with relaxed ease, discovered a jam session in progress and decided to join in the fun. The guitars may have been of the Baroque variety, the drum kit replaced with tambour and tambourine, and the bass-line provided by a violone, but last night mezzo-soprano Magdalena Kožená fronted quite the coolest gig in town.