In 1964, Mary Whitehouse launched a campaign to fight what she called the ''propaganda of disbelief, doubt and dirt'' being poured into homes through the nation''s radio and television sets. Whitehouse, senior mistress at a Shropshire secondary school, became the unlikely figurehead of a mass movement for censorship: the National Viewers'' and Listeners'' Association, now Mediawatch-uk.

For almost forty years, she kept up the fight against the programme makers, politicians, pop stars and playwrights who she felt were dragging British culture into a sewer of blasphemy and obscenity. From Doctor Who (''Teatime brutality for tots'') to Dennis Potter (whose mother sued her for libel and won) to the Beatles - whose Magical Mystery Tour escaped her intervention by the skin of its psychedelic teeth - the list of Mary Whitehouse''s targets will read to some like a nostalgic roll of honour.

Caricatured while she lived as a figure of middle-brow reaction, Mary Whitehouse was held in contempt by the country''s intellectual elite. But were some of the dangers she warned of more real than they imagined?

Ben Thompson''s selection of material from her extraordinary archive shows Mary Whitehouse''s legacy in a startling new light. From her exquisitely testy exchanges with successive BBC Directors General, to the anguished screeds penned by her television and radio vigilantes, these letters reveal a complex and combative individual, whose anxieties about culture and morality are often eerily relevant to the age of the internet.

''A fantastic read . . . I can''t recommend it highly enough.'' Lauren Laverne, BBC Radio 6 Music