Kneehigh are a very good example of a theatre company that straddles the gap between 'fringe' and 'mainstream’ – showing that there is little currency left in those terms as exclusive divides. With Tristan and Yseult at the National, Wagstaffe tours the village halls and scout huts of south-west England, ending in a run at BAC (which at a stretch we could think of as Battersea's village hall). Billed as the only show this year starring a clockwork boy and an articulated lorry, it's about a boy so bad his parents run away from home to join the circus. This is an unashamedly populist family show – with a typical Kneehigh mix of beefy physical performances (air guitar, circus tricks and karaoke), quirky visuals (including Wagstaffe's stunning transformation to cyborg then angel) and ironic humour. Much of this humour revolves around Wagstaffe's reputation as 'bad' – he is of course a delightful young person, whilst his parents are seen as being so tied up in themselves that they can't manage to work out that he has needs. This inversion of what is presented as truth is explored with a lack of polemic so that the message – that each individual is a unique wonder – can be discovered by the audience in their own way. As in all Kneehigh productions, music plays on important part, in this case some very fetching rock classics from Led Zep and Meat Loaf. It's great fun, it's good theatre – and despite (or even because of) the constant high level of humour, it is in the end, profoundly moving. But there again, I'm the girl who cried when Champion the Wonderhorse died, so I've always been a sucker for corny, popular drama that tugs at the heart-strings.