Len Deighton reveals how he wrote SS-GB, the bestseller that imagines Hitler had won the war

“Perhaps. But what kind of book?”

“An ‘alternative world’ story,” said Ray.

Ray had been a classmate at the Royal College of Art and had contributed a great deal to the success of my books. Not only did he design the dust jackets (his Ipcress File cover was a game-changer) but all manner of other sensational promotional accessories. For SS-GB he would produce booklets of British Hitler-head postage stamps that have become much sought-after.

Len Deighton in 1966

But I was not immediately attracted to the idea of an “alternative world” story. I had avoided anything in the nature of science fiction or fantasy and, as always, my next three years of writing were already roughly planned. It was the mid 1970s and I’d become a writer almost by accident. For much of my working life I was an illustrator. Yet, despite my lifelong concern with pictures, and an inclination to judge everything for colour and shape, books consist of 100 per cent words. Words are a writer’s only currency and it is his task to confide his story to the reader; confide as to a trusted and intimate friend.

No wonder then that I spend so long in preparation and research, and then work slowly and nervously preparing a story-structure. I worry about each page; deleting paragraphs and improving words, with a gigantic, well-thumbed dictionary at my side.

For books, as with cooking, building and probably with many other things in life, it’s the long and careful preparation that is decisive. Initial ideas for books arrive in fits and starts. An environment and the characters usually provide the beginning. Those decisions steer me to the mood and writing style. Is it to be written in the first person or third person? Is it historical or up to date? Is there to be an element of comedy?

Ray’s suggestion did not fade but there was one big obstacle. Who would be the central figure – the hero – of my grim tale? A German? We had lived in Germany and I knew many Germans of widely differing political pasts. I’ve always been a risk-taker (you can ask my wife about that) and writers must take risks if they’re to progress and improve. But I baulked at creating a German central figure. It had to be someone moving in the upper circles of the German administration in order to tell the story in the way I wanted. But I didn’t relish attempting to create a sympathetic English collaborator; a Quisling! My man couldn’t be a war hero, they would all be dead, in hospital or in PoW camps. He couldn’t be a fugitive; I needed to describe England, and the occupation, without such constraints.

Scotland Yard in the BBC1 adaptation

I almost abandoned the project at that stage but I was enjoying lunch at a fish and chip shop in Marylebone with the writer Ted Allbeury – telling him all my troubles – when a solution jumped up and waved a red flag. Ted, before starting his career as a novelist, was a senior Army intelligence officer. He was the only English agent parachuted into wartime Germany. Stationed in postwar Germany, he became the man the local Germans persisted in calling the head of the English Gestapo (“...eventually I stopped correcting them,” said Ted).

Exactly how the final idea for SS-GB emerged I cannot remember, but by the time we reached the steamed golden pudding my central figure was beginning to look like a London copper. Later that night I fleshed out this “hero”. Douglas Archer would be a celebrated Scotland Yard detective of the “murder squad”. As such he’d sit at the heart of the German authority but not be a contributor to the repressive Nazi regime.

This didn’t mean that I could start writing. The research wouldn’t be easy. The London of the 1970s had altered a great deal since 1941. Architecture, communications, policing and politics had changed fundamentally. If I was to write with the authenticity that my story demanded, I would have to tread warily through a minefield of anachronisms. But I was old enough to remember London in 1941 vividly.

So I decided that most of the scenes described in the book would be places I remembered; my home, my school, my neighbours and my local shops. And I remembered the bombed buildings, the blacked-out streets, the tin baths, the food rationing, the shortage of fuel and thus of hot water. And I remembered the brave Londoners; their concealed anxieties, studied composure and their prevailing sense of humour.

Kate Bosworth and Sam Riley in SS-GB

By the 1970s, the old Scotland Yard building – where my Archer would have his office – had been converted into offices for senior politicians and civil servants. It was out of bounds to everyone else. It loomed as an insurmountable obstacle. It was my old friend Freddy Warren, from the Whip’s Office, who waved a magic Westminster wand. He not only arranged for me to wander through this “Parliamentary building” at will, but also found a retired policeman to guide me on my wanderings, providing a commentary about “the good old days”.

The Metropolitan Police gave me unlimited access to their archives and museum. For day after day, I studied photos of 1940s detectives in mandatory suits and ties, plus details of real wartime crimes. This privileged kindness contributed greatly to my knowledge and my book.

I anticipated resistance to my research trips. I worried that people would refuse to help a writer describe a German victory and a subservient Britain. I needn’t have; I encountered no opposition nor criticism. Some were amused, some were perplexed. Some expressed hatred of the Germans and relief at our ultimate victory. But everyone I spoke with trusted my judgement in describing these fictional, but nonetheless controversial, events. And this was also the case when I spoke with German veterans, including army generals and some senior SS officers.

There were many more decisions to be made before I started. As an overall plot, I decided that a detective story format would inflict a necessary discipline on the story. A murder committed on page one would be solved at the very end. I studied the German plans for the occupation. I didn’t stick rigidly to these, but the Germans might not have stuck to them either. I drew a wall-chart of the German chain of command; army, SS, British puppet government and civil police. I looked at newsreel film of postwar Germany and the other occupied countries.

The tone-colour of the story was to be grey, like the SS uniforms. The season must be winter; the mood bleak and cold. So it was fitting that I started writing it in an old mountainside house in Tuscany. Never mind the tourism posters, that winter in Italy was icy cold. My wife and two small sons were there to watch my hands swell and grow purple as I bashed the keys of a locally purchased manual typewriter. (I had searched high and low in Barga, the nearest town, to buy an electric typewriter but without result.)

Another problem emerged; this time it really was insurmountable. As I neared the end of that first draft I found that the first-person format could not be sustained. A man, even my detective Douglas Archer, couldn’t be in London and on a ship at sea at the same time. I dumped that draft, bought another ream of paper and started afresh. There are moments in a writer’s life when other ways of earning a living become remarkably attractive.