The American Library Association recently published its list of books that people tried hardest to ban between 1990 and 2000, with the Harry Potter series in seventh place – just after Huckleberry Finn and Of Mice and Men.

Among the ALA's top 100 endangered books are SF and fantasy by Madeleine L'Engle, Roald Dahl, Margaret Atwood (The Handmaid's Tale), Daniel Keyes (the innocuous Flowers for Algernon), Aldous Huxley (Brave New World, of course), Stephen King, and Kurt Vonnegut (Slaughterhouse-5). Even William Golding's classic Lord of the Flies gets a mention. Book-banners are a strange, illogical bunch.

The tradition goes back a long way. One of the earliest fantasies to be officially banned was Homer's Odyssey – by the Emperor Caligula in AD 35. Being clinically bonkers, Caligula felt that this epic taught Greek ideals of freedom, which obviously wouldn't do in Rome.

Skipping ahead to 1497, Ovid's Metamorphoses (full of shape-changer fantasies) and Dante's Divine Comedy (more influential in SF than you might think) were burnt by order of that fiery reformer Savonarola: Ovid for being erotic and Dante for "vanities". A sixteenth-century Archbishop of Canterbury agreed about Ovid, and burnt his works in 1599. Sir Thomas More didn't dare publish his 1516 SF satire Utopia in England or indeed in English, for fear of Henry VIII's wrath at the digs about royalty. It appeared in Latin, overseas only, and for other reasons Henry had More executed anyway.

My favourite twentieth-century case is the 1920 banning of James Branch Cabell's witty, harmlessly naughty fantasy Jurgen, thanks to John S. Sumner of the New York Society for the Suppression of Vice. In the resulting trial, the publishers were acquitted – partly because the judge believed the book's solemn but totally untrue introduction claiming that it was "based on the medieval legends of Jurgen".

The publicity sent Jurgen's sales sky-high, and Cabell's next book was respectfully dedicated to his benefactor John S. Sumner, who'd "glowingly advertised" him to the public. Cabell claimed to be specially impressed by Sumner's ability to unearth sexy meanings in anything: "I have applied your method to many of the Mother Goose rhymes with rather curious results ..."

Publicity was equally rewarding for the pulp supernatural/horror magazine Weird Tales in 1924, which according to legend sold out fast when readers heard that many newsstands had banned it. The reason was C.M. Eddy's "The Loved Dead", a ghoulish story about a necrophiliac serial killer, revised for publication by the not yet famous H.P. Lovecraft.

Closer to home, the Irish Republic traditionally banned all sorts of things disapproved of by the Vatican – including Brave New World, for general immorality, as late as 1932. (Amazingly, this and Animal Farm remained forbidden into the 1950s in freedom-loving Australia.) It was W.H. Smith's rather than Parliament that halted UK sales of Michael Moorcock's uninhibited, subversive New Worlds magazine in 1968. In the early 1990s, Manchester police came down heavily on David Britton's satirical, deliberately offensive anti-Nazi fantasy Lord Horror, with the odd legal result that the novel was saved from a destruction order in 1992 while the graphic novel stayed banned. Books are for adults, but comics are for kids who must at all costs be protected.

Censors usually end up looking silly in the clear hindsight of history. A splendid example is the late Spike Milligan's surreal post-nuclear-war stage comedy The Bed-Sitting Room, written with John Antrobus and later made into a cult movie. It launched in 1963, when that dread court official the Lord Chamberlain could still shut down British theatres for staging unapproved plays.

For decades, Milligan treasured the Lord Chamberlain's official letter, on embossed royal notepaper, approving The Bed-Sitting Room if certain changes were made. It begins boringly: "Omit the name of the Prime Minister: no representation of his voice is allowed." Next, Milligan was told to delete the words "clockwork Virgin Mary made in Hong Kong, whistles the twist." Next, "Omit reference to the Royal Family ..."

The Chamberlain droned on: "The mock priest must not wear a crucifix on his snorkel." "Omit 'crap' substitute 'Jazz'." More lines were chopped, from "We've just consummated our marriage ..." to "The Duke of Edinburgh is a wow with Greek dishes." The final demands: "Omit '... the perversions of the rubber ...'. Substitute '... the kreurpels and blinges of the rubber'. Omit the chamber pot under bed."

And that, readers, is how the British public was protected from the SF drama of Spike Milligan.

David Langford wrote "****" here once, but SFX substituted asterisks.