Edinburgh Festival: Good heavens, they're alive!

Sherlock Holmes and Doctor Watson are more than 100 years old and still in the detective business.

In an exclusive interview, David Benedict talks to the World's Greatest Detective and his chum

WE'VE NEVER met before, but within seconds of my arrival at a secret address in Covent Garden, he's pinned me down. To my astonishment, he knows where I've come from and my mode of transport.

"But how?" I cry, baffled by his legendary perspicacity. He fixes me with a beady eye. "By the small dark patch on the left handle of your briefcase. It suggests a limey dirt track of the kind only to be found near the Elephant and Castle. You must have slipped on the way due to a loose horseshoe." Apart from the taxi, he's right in every particular.

Even if it weren't for the masterly deduction, there's no mistaking the cloak, the pipe, and the gaunt, knife-edged profile jutting out beneath the deerstalker. I am in the presence of Sherlock Holmes. Had it not been for the peculiar demise of the trapeze artist Flying Fernando and the devilishly cunning Garibaldi Biscuit Affair, we might never have known the truth. When the trusty Sir Arthur Conan Doyle died in 1930, the world assumed that Holmes and his sidekick Dr Watson had gone with him. But no. They're very much alive.

Once and for all they are putting to death the vicious rumour that they are fictional characters. After months of delicate negotiations, the two bachelors have agreed to come out (of hiding) and talk - and do they have scores to settle? Does Mrs Hudson bake a mean fish pie? Conan Doyle made a pretty penny out of them with four so-called "novels" and 56 "short- stories" but they never saw a penny in royalties, although, in Holmes's words, "We're modest men. We live together in our flat at 221b Baker Street." Alone? "We don't like to talk about it."

Nevertheless, their reputations have been sullied in over 50 plays and 150 films. They regard themselves as having been immortalised in the thoroughly respectable pairing of Basil Rathbone and Nigel Bruce. Billy Wilder's film The Private Life of Sherlock Holmes, however, found Robert Stephens nursing a nasty cocaine habit. "If we'd had a better lawyer we'd have sued," exclaims Holmes.

They had even less time for Gene Wilder as Sherlock Holmes's Smarter Brother, aided and abetted by Marty Feldman. Gerry Rafferty used up all his inspiration trading on their association in his sax-drenched one-hit wonder "Baker Street", and Ron Moody widened his repertoire of famous Londoners playing the title role in Sherlock Holmes, The Musical. This less-than-toe-tapping tuner included such capital treats as "London is London", "Down the Apples`n'Pears" and the existential duet for its lead characters, "Without Him, There Can Be No Me".

The world is still waiting for Sherlock Holmes - The Opera, but their most sublime manifestation yet was undoubtedly 1953's The Great Detective, which, I regret to inform you, was a ballet. This strangely neglected jewel, the first (and last) full-length work of one Margaret Dale for Sadler's Wells, featured the corps de ballet dancing the Murderous Villains and Respectable Folk. The dual role of The Great Detective and The Infamous Professor (Moriarty) was created by none other than Kenneth MacMillan who, in the climactic scene, displayed "The Detective's mastery of the art of ju-jitsu, upheld the law and, with the assistance of his disguises, performed his Dance of Deduction."

Holmes and Watson agree that the Royal Ballet could do no better than to revive it for the re-opening of Covent Garden. All this time, the once and future detective and his friend have been pondering over their enduring fame. "The sound of horses' hooves on cobbled streets, the fog - that's always attractive," proffers the roly-poly Watson. "It's Merchant/Ivory meets Inspector Morse with a bit of The Forsyte Saga thrown in. People just lap it up." Holmes nods, agreeably. "Yes, our characters are appealing, aren't they? You've always called me an enigma, but actually I'm a gentleman." "And I'm just a blithering idiot," beams Watson. "True," remarks Holmes, puffing away at his pipe. "No one would be interested in your adventures." As Holmes points out, even Watson's name is nondescript. "His mother said, `I'm going to name him after the first person I see'. So there he is: Doctor Watson. The man has nothing to do with medicine."

This male-bonded banter conceals tensions in their relationship. Watson has nothing but open-mouthed praise for "Holmes's enormous deductive organ", but he's also deeply troubled. As visitors to the University of Minnesota (repository of the world's largest collection of Sherlock Holmes memorabilia) will attest, there's the nasty business of the needles: Holmes is a self- confessed addict. "Yes!" he cries, his wild eyes racing from his violin to the works in his pale hands. "French Knitting! I'm busy on a sideboard cover and an eye patch to wear on the train to the Edinburgh Festival."

So all that drugs talk is trumped up? "Oh no. I do that too," he smiles, blithely. Watson explodes in despair. "If only we'd had a drugs czar in 1898," he wails. "I can't bear to see you destroying your brilliant mind. You cut out everything. You cut out your work, you cut out your friends, you cut out strings of little men from folded-up copies of The Times - I can't bear to watch it happen!"

He's suggested 12-Step programmes and even breathed the words "Betty Ford", but: "He won't listen to me. It's only when his deductive organ isn't being used. It turns in on itself and heads off to the medicine chest. I've tried hiding the key." "Yes," whispers Holmes. "But always in the same place."

But no one can beat Holmes. They have little time for the subsequent jumped-up parvenus. They pooh-pooh the amateurishness of Miss Marple, the pomposity of Poirot or the flavourlessness of Inspector Wexford. They see themselves as the beginning of a line that has led to Amanda Burton in Silent Witness. "I've lent her the deerstalker for the next series," observes Holmes.

Their enduring prowess can be seen in Move Over Moriarty, the dramatisation of their latest perplexing case. They've narrowed the list of suspects down to the habitues of a music hall. Who is the murderer who strikes and leaves behind the Garibaldi biscuit? Death-Defying Dan and his Whelk- Infested Tank of Terror? Or the male impersonator, Miss Vesta Curry, and her Novelty Pipe-Smoking Act? Could it be Elsie Linnett, the Generously Proportioned Bulgarian Songthrush?

One thing's for certain, literature's biggest names are fighting over the affair of who should chronicle their continuing exploits. The words "Martin" and "Amis" are in the air. "He could start with the solution and then work backwards to find out who's been killed," muses Holmes. "But we've found the solution." Who is it to be? "Elementary, my dear - Jeanette Winterson."

Maggie Fox and Sue Ryding, aka Lip Service, play Holmes and Watson in `Move Over Moriarty' at the Assembly Rooms, 0131-226 2428