The devil and Diana Mitford

After the success of his first Lucifer Box novel, the League of Gentlemen's Mark Gatiss turned his attention to the thrilling tales of the 1920s and 1930s to inspire his colourful sequel

'He had been shut up with Baden Powell at Makefing and knew a thing or two." I discovered this curiously attractive sentence in an anthology of boys' stories published in 1928 under the lovely title of Chums. Within its pages are tales of rugger players and pirates, diabolical foreign masterminds and fat fags on paper chases that are toxically alluring (and perhaps literally toxic as the stuff that was used in the printing process has, over the long years the pages remained closed, bled out to form a gorgeous shimmering lattice like silver in rock). I found this volume of ripping yarns while researching my new novel, The Devil in Amber, the follow-up to The Vesuvius Club, which again features Lucifer Box, painter, secret agent, bisexual rake and resident of Number Nine, Downing Street (well, somebody has to live there).

The reason I was trawling antiquarian bookshops is intimately bound up in the original commission I received from the publishers Simon and Schuster. The Lucifer Box books (the Box-set, you might call it. Though the name came before the marketing opportunity, I swear) had originally all been envisaged as being set in the Edwardian era. This swirling, gas-lit world of Conan Doyle, Sax Rohmer, consumption and "London Particulars" has always been a favourite and I giddily launched into re-reading my favourite tales in order to steep myself, once again, in the crimson and stained-velvet flavour of the period.

By the time I'd finished the first adventure, however, having had my hero fall into studies both brown and scarlet, his breath smoking like pistol shot in the freezing dawn, I'd had a new idea. Instead of simply carrying on in the same vein of Chinese opium dens and venomous centipedes, I decided to try something bolder. Putting aside a storyline set in St Petersburg featuring a dangerous new brand of absinthe that brought its victims under the control of a crazed proto-Bolshevist cabal, I moved the action on some 20 years, placing an older Lucifer Box into an entirely new era. Having being deliberately vague about Box's age in the first story it was possible to imagine him middle-aged and under threat in a different setting: amidst the sleek lines of an Art Deco landscape somewhere in the late Twenties or early Thirties. The thrillers of this period were much less familiar to me but I waded into them with a passion for which the term "guilty pleasure" could have been coined. Devouring Buchan (hugely influential, though the fantastic Thirty-Nine Steps and others actually belong to a slightly earlier period) and Sapper's Bulldog Drummond stories, I embraced the terser, less purple style of the period; a world of wiry, sunburnt patriots ("lean and brown" as Buchan always has it) trying to keep the British end up against a colourful array of shifty types bent on bringing Socialism to our shores. Imagine that! I was pointed towards a once hugely popular novelist called Dornford Yates, best known now for his "Berry" books but whose thrilling tales of buried treasure and Alpine inns are just as addictive. One of his heroes, nailing his patriotic colours to the mast, has been sent down from college for beating up Communists.

I spent many a happy hour scrawling copious notes to try to get the style of the period and I have pages and pages littered with phrases like "he played a bold hand", "every detail of the hellish contrivance" and "I had a good deal of fever in my bones".

It was important to me, though, that I retain the same brief I'd set myself for the first story. Just as that book was both a pastiche and a bit of cheek, I wanted to blend all these fabulous new ingredients into something different. In The Vesuvius Club I'd tried to turn a sputtering dark-lantern on to some of the naughtier aspects of fin de siècle society, the bits that exist in the shadows of Sherlock Holmes. This time, in order to keep the flippant first-person style of the first story, I tried to temper - with Box's native loucheness - the terser style of the period and, in doing so, give some of the era's characteristic dialogue style to others. An interesting presence in several of these kind of thrilling stories (or "shockers" as they were known) is the silly-ass Englishman whose facetious manner disguises an inner steel. This seems to have sprung up in World War One as officers took their childhood language (or "lingo") into the trenches (or "the Show") droppin' their g's, pullin' thoughtfully at their pipes and grinnin' at the whole dashed madhouse, don't you know, from behind their well-polished monocles. Such verbal tics, a sort of oh-so-English defence against the horrors of the trenches, is best exemplified by Dorothy L Sayers' Lord Peter Wimsey, a terrific character whose breezy manner conceals a tormented soul, plagued by nightmares of his time at the Front. I gave this flippant attitude to Percy Flarge, a bright young Academy agent who's after Box's job, though in his case the silly-ass manner seems to conceal something altogether more sinister.

In addition to the Boy's Own flavour, I knew from an early stage that I was keen to add a dash of Satanism into the mix. And if we're talking Satan and escapist fiction then there's only one name: Dennis Wheatley. When I was a boy, obsessed with Hammer films and all things lurid, Wheatley's name was like a talisman (or, more likely a waxen effigy covered in hair, fingernail-clippings and beads of black blood) and my Dad, an avid fan, had loads of the stories in cloth-bound, book club editions he'd ordered in the 1950s. Arranged on the shelf next to my collection of Doctor Whos, they promised a glimpse into the exciting adult world of The Eunuch of Stanbul, The Forbidden Territory and V for Vengeance. However evocative these titles, though, they were only Wheatley's adventure stories. The true prizes were the well-thumbed Pan paperbacks of the Black Magic tales for which the author is still best remembered; fat tomes with naked girls, black candles and terrifying goat's heads on their covers that exerted a real hold on me - part terror, part thrill, part pre-pubescent giddiness of the type only a bared female breast could then engender. The Haunting of Toby Jugg! The Irish Witch! and, best of all, The Devil Rides Out, which I already knew from the Hammer film. Few things in horror rival the moment when the lights of Christopher Lee's motor car are brought to bear on the hideous apparition Charles Gray has summoned at his sabbat. "The goat of Mendez!" hisses Lee. "The devil himself!" This film left me in a state of palpitation that was unusual in my Friday night horror fix (it was called Appointment with Fear in the Tyne-Tees region). I could take vampires, werewolves, zombies but the Devil... well, there was something forbidden, something terribly real about it that left me absolutely petrified.

With this in mind, I set about re-reading Wheatley. Once the most popular writers of his time, the old boy is now out of print but once again my Dad came to the rescue, locating an entire set of leather-bound Wheatleys in a charity shop. I worked through the Gregory Sallust tales but the real star was once again The Devil Rides Out - an absolutely corking read: dynamic, thrilling and incredibly un-PC. Taken in context, along with other writers such as "Sapper" and Agatha Christie, these stories provide a fascinating glimpse into the casual anti-Semitism and racism of the world between the Wars. "He's a 'bad black' if ever I saw one," comments the Duc de Richleau of a Malagassy servant, "and I've travelled, as you know, in my time."

But how to convey something of this period flavour without simply parroting the hateful attitudes of the time? The answer lay with the other element I knew I wanted in this devil's brew: the rise of Fascism. In the new story, Box is assigned to keep an eye on the leader of an organization called FAUST - the Fascist Anglo-United States Tribune. As Box comments, it's an acronym so tortuous it can only be sinister. It's no accident, of course, that this leader, Olympus Mons, shares his initials with Oswald Mosley, a figure who's always intrigued me and whose life is a fascinating study in hubris. I immersed myself in Harold Nicholson's diaries and biographies of both Mosley and the Mitford girls to build up as full a picture as possible of the heady political scene of the time: a world where reasonable people seriously debated the notion of totalitarianism as the only antidote to world depression.

As usual with such research, not much of it made its way into the book, though I gave Mosley's famous "lighthouse" stare to my villain and Mosley's wife Diana (whom I think I first encountered on Sue Lawley's infamously soft Desert Island Discs interview) and her charmingly crazy family conjured up a new character: Lucifer's sister. It was the extraordinary Unity Mitford, of course, who was the main inspiration; the Hitler-obsessed girl who hung about in the Fuhrer's favourite café until he noticed her and who shot herself in the head at the outbreak of war. The pictures of her in belted mac and severely bobbed hair (before the war) and saucer-eyed and nearly imbecilic (after the shooting), fascinated me and she became the model for Lucifer's icy but naïve sister. All heroes should have unusual siblings. It's par for the course. Holmes had one. Even Poirot has one; a moustache-less brother called Achille (though he turns out to be Poirot in disguise).

So, with all the elements in place, The Devil in Amber is ready for release. I've intended these books to be the sort of thing I'd love to read on holiday and I hope that's the sprit in which they're taken. I'm planning a third adventure in which a very old Box finds himself in early Ian Fleming territory and can't wait to start the research!

By the way, I absolutely had to call Lucifer's sister Pandora. I suppose it should really have been Pandora S Box, but you can't have everything.

* 'The Devil in Amber' by Mark Gatiss is published on 6 November by Simon & Schuster (£15). To buy a copy for £13.50 (free p&p), call Independent Books Direct on 08700 798 897, or post your order to them at PO Box 80, Helston TR13 0TP.

* Mark Gatiss will be reading from the book and signing copies at Foyles, Charing Cross Rd, London WC2 at 6.30pm on 16 November. Call 020 7437 5660 for details.