The Antiques Roadshow visits Ashton Court in Bristol, where intriguing finds include a nautilus shell engraved with Brunel's suspension bridge, an automaton that smokes and, the newest item the team have ever seen, a piece of Banksy graffiti. The latter was discovered in a doorway close to a local youth club. Pictures specialist Rupert Maas offers his thoughts on the murky world of authenticating illegal graffiti and an artist whose identity is a well-kept secret. 

Hilary Kay admires a nautilus shell engraved with an image of the city's famous suspension bridge, while ceramics specialist John Sandon wonders if a delftware posset pot might have originated much closer to home. 

A large globe clock, once given in lieu of a debt, turns out to be far more significant than its owner could ever have imagined. A late 19th-century automaton of a young French gentleman steals the show by smoking a cigarette, only to be promptly told off by specialist Jon Baddeley