When I was a mere lad [Oh God, not again – Ed.] there wasn't enough SF published every month to feed my desperate appetite for cheap thrills, and I had to diversify into crime fiction. What I didn't know was that some of those detective stories were actually by familiar SF names in clever plastic disguises.

For example, the mystery author Ellery Queen, who usually wrote about a highly intellectual detective called Ellery Queen, was normally a couple of cousins working in collaboration: Frederick Dannay and Manfred B. Lee. But late in his or their career, "Queen" took to having occasional books ghost-written by SF authors.

Thus the Queen novel And On the Eighth Day, with its sympathetic treatment of an offbeat religious cult, turned out to be by that most eruditely Jewish of SF authors, Avram Davidson. Davidson also ghosted another Queen thriller, The Fourth Side of the Triangle. Theodore Sturgeon's twisty insights into morbid psychology transferred neatly from his SF to the "Queen" novel The Player on the Other Side.

A lesser-known SF hack, Paul W. Fairman, ghosted stuff under a variety of names; he's the answer to a famous trick question in SF quizzes, "Who wrote The Runaway Robot by Lester del Rey?" His contribution to the Ellery Queen saga was to novelise the script of the Sherlock Holmes film A Study in Terror, based not on Conan Doyle but on a short Queen story. Fairman wrote the book – also known as Sherlock Holmes versus Jack the Ripper – from the viewpoint of Doctor Watson. Then the real Queens, Dannay and Lee, added a second narrative strand in which EQ the detective reads the "lost" Victorian MS and corrects Holmes's solution of the Ripper mystery! So it's really a collaboration.

In later years I discovered a second series of what you might call Queen potboilers, which never featured the sleuth Ellery Queen and weren't classy enough to appear in nice Gollancz hardbacks. Three of these – The Four Johns, A Room to Die In and The Madman Theory – proved to be by SF old-timer Jack Vance. He's notorious in SF and fantasy for wonderfully, ornately witty prose, but even though he's won major crime fiction awards when writing as John Holbrook Vance, his thrillers are frankly boring.

So much for all the SF authors who were Ellery Queen. Others dipped their sticky fingers into the works of Leslie Charteris, creator of the Saint. I discovered the Saint stories at an early age, thanks to one early novel featuring the SF gimmick of a Weapon Too Dreadful To Use, the fearsome "electron cloud", invented by a mad scientist who gets his proper come-uppance: "I shot him like a mad dog." Naturally I was shocked to learn that according to critical experts, most of the Saint books after about 1940 were ghost-written ... often by SF writers.

(A few 1970s Saint TV script novelisations are correctly credited to writers who aren't Charteris, but there's no deceit there.)

Henry Kuttner, still remembered by the cognoscenti for Fury, Mutant, and much other SF, was involved. According to the evidence, he expanded a script from the 1940s Saint radio show into a novella published under Leslie Charteris's name, just possibly after some titivation by Charteris himself: "The King of the Beggars" in Call for the Saint.

It is absolutely certain that Harry Harrison, creator of the Stainless Steel Rat (come to think of it, not entirely unlike an SF version of the Saint), wrote the 1964 "Charteris" novel Vendetta for the Saint. This was based on an unused Saint comic-strip continuity which had been written by some guy called ... Harry Harrison.

When Theodore Sturgeon – him again – died in 1985, one obituary gave him credit for ghosting one of the rare Saint fantasy stories, "The Darker Drink", also known as "Dawn". I dutifully recorded this in The Encyclopedia of Fantasy, but there's been much controversy on the point. After considerable debate, many experts (a term which here means "David Pringle") think this story was ghost-written by another SF author, Cleve Cartmill.

Now Cartmill was famous for putting a scare into the American security services in 1944, when Astounding SF published his story "Deadline" – describing the atomic bomb a year before Hiroshima. (In Cartmill's version, the evil "Sixa" forces are prevented from dropping the bomb, and the good "Siella" are too moral to use it. What could those cryptic codenames mean?) Astounding's editor John W. Campbell was severely questioned, but pointed out that all Cartmill's information came from public libraries.

After careful stylistic analysis, that awesome SF authority David Pringle is also convinced that Cleve Cartmill also wrote a whole novel under the Charteris byline, The Saint Steps In (1943). Additionally, Pringle believes that Theodore Sturgeon – him yet again – is responsible for The Saint Sees It Through (1946) ...

You can't trust anyone in this business. Any minute now, we'll be hearing such wild accusations as that the great William Shatner's TekWar novels were actually written by SF author Ron Goulart (who is mysteriously acknowledged in the first for his help). Oh. Oh, they were, were they? I'll get my coat now.

David Langford once published a Sherlock Holmes story which, believe it or not, was authorised by the Conan Doyle estate.