PETER ACKROYD IS fascinated by the associations that particular places take on over the centuries and which come to define their character. 'The history of London', he argued in his marvellous, slightly mad book London: The Biography, 'is a palimpsest of different realities and lingering truths.' Take Clerkenwell, on the western edge of the square mile, for example. It has been a centre of radical activity for the past six hundred years. Wat Tyler, leader of the Peasants' Revolt in 1381, camped on Clerkenwell Green after torching the nearby priory of St John. Chartists, Fenians, suffragettes and trade unionists have all gone there to rally support for their causes. William Morris and Eleanor Marx addressed crowds from a balcony of what is now the Marx Memorial Library, also on the edge of the Green. There, in 1902, Lenin edited his newspaper Iskra from a small first-floor office.

Ackroyd's latest novel is a meditation on the fourteenth-century origins of this radical aspect of Clerkenwell's history. It seethes with conspiracies, plots and counterplots. The story unfolds in 1399. Sister Clarice, a nun at the House of St Mary, is having visions of King Richard 11's imminent deposition by Henry Bolingbroke. News of these