When Christopher Somerville, author of the 'The January Man', set out to explore Britain's cathedrals, he found his fixed ideas shaken to the roots. Starting out, he pictured cathedrals - Britain possesses over 100 - as great unmoving bastions of tradition. But as he journeys among favourites old and new, he discovers buildings and communities that have been in constant upheaval for a thousand years. Here are stories of the monarchs and bishops who ordered the building of these massive but unstable structures, the masons whose genius brought them into being, the peasant labourers who erected (and died on) the scaffolding.