Several stories below the British Library's Magna Carta room, alongside a rumbling line of the London Underground, is a brightly lit labyrinth of rare and historic items. Past a series of antique rifles chained to a wall, past an intricate system of conveyor belts whisking books to the surface, the library stores an enormous collection of plays, manuscripts, and letters. Last spring, I checked my belongings at security and descended to sift through this archive a record of correspondence between the producers and directors of British theater and a small team of censors who once worked for the Crown.

For centuries, these strict, dyspeptic, and sometimes unintentionally hilarious bureaucrats read and passed judgment on every public theatrical production in Britain, striking out references to sex, God, and politics, and forcing playwrights to, as one put it, cook their "conceptions to the taste of authority." They reported to the Lord Chamberlain's Office, which in 1737 became responsible for granting licenses to theaters and approving the texts of plays. "Examiners" made sure that no productions would offend the sovereign, blaspheme the Church, or stir audiences to political radicalism. An 1843 act expanded the department's powers, calling upon it to block any play that threatened not just the "Public Peace" but "Decorum" and "good Manners."

"OMIT THE BUSINESS AND SPEECHES ABOUT FLYBUTTONS."

Hardly chosen for their artistic sensibilities or knowledge of theatrical history, the men hired by the Lord Chamberlain's Office were mostly retired military officers from the upper-middle class. From the Victorian era on, they scrutinized plays for references to racial equality and sexualityparticularly homosexualityvulgar language, and "offensive personalities," as one guideline put it.