Asked by a beggar if he has any change, toff, George Balfour replies: "Really sorry, I've only got notes." There is a lot of humour in Posh. This developingly grim drama is about the appalling behaviour of young gentleman in The Riot Club, the Bullingdon Club by another name. There is a strong opening to Laura Wade's play. A superb set by Will Coombs takes us first into the House of Lords where young student Guy Bellingfield (henceforth known as Bellend) is asking asking his godfather Jeremy for advice. He wants to restart the Riot Club after it has been banned for too much bad press. (Whatever other kind could it have - it exists to smash up restaurants). Strong performances here from Adam Mirsky as Guy, channelling a pink-faced, earnest, youthful Boris type creature, full of puppy-like bounce. Simon Rhodes as the peer exudes the now mature Hooray Henry, cheerfully reminiscing about the damage done in his day and despising the restaurateur for the poor peasant's delight at how well he was being reimbursed. This better class (and very thorough) group of vandals had removed the skirting boards and the wiring. They always pay up to buy off charges of criminal damage. The curtain next opens on the rich-red flock wallpaper of a pub dining room. The table is set for a smart dinner. We meet the 10 diners, all nuanced variations on the posh boy, not terribly clever but each completely convinced of his entitlement to tread on the rest of the world. There is talk of the distress of stately homes being opened to the public. Someone laments that the date of his sister's wedding had to be changed because of a teddy bears' picnic. Tyger Drew-Honey's character Alistair Ryle launches a tirade on how the lesser classes don't understand the value of things. They haven't inherited anything, they have no provenance. They are not custodians of a tradition so how can they know about anything. The speech is delivered with such convinction you almost start to see its point. When it comes to the drunken trashing-up of their fine dining surroundings, we have a balletic scene with the actors moving in slow motion to music from Swan Lake. A fine piece of artistry. Plaudits must go to Peter McNeil O'Connor as the publican and Isobel Laidler as Rachel his daughter, for touchingly natural performances. The building menance is so real, you want to call out to save them. It's over two hours in revolting company, but so well done, so sparkingly written, deftly performed and well directed by Lucy Hughes, that it is a fine piece of theatre. Posh is at Cambridge Arts Theatre until Saturday, September 21.