By the time the cannons fell silent across Europe in 1945, the leading architects of fascism were dead. Mussolini was hung upside down from a metal girder in the Piazzale Loreto and Hitler hurriedly cremated after committing suicide in Berlin.

With much of Europe turned to rubble, few families left untouched and the newsreel footage of Jewish bodies being pushed into mass graves seared into societal consciousness, most understandably thought that fascism would die with its founders.

In 1946 the British journalist, author and anti-fascist Frederic Mullally stated that: “In the midst of the uncertainties and hazards of war, here we thought, was one thing that could be taken for granted: fascism had had its day in England; there could be no ‘come back’.” Yet the truth is that during the war years there were fascists in England working to keep the flame alive, and even before the killing had stopped British fascists were readying themselves to relaunch in the hostile postwar period.

It is this re-emergence of fascism in Britain that I cover in my new book, British Fascism After the Holocaust: From the Birth of Denial to the Notting Hill Riots 1939-1958.

In it I set out to understand how it is that some people remained unmoved by the horrifying revelations of the Holocaust. How after news of Belsen, Auschwitz, Treblinka, Belzec, Buchenwald and Chełmno so many refused to turn away from fascism and antisemitism. The answer is a complex one that sheds light on the tragic persistence of antisemitism and the cockroach-like adaptability of fascism — and continues to have relevance to this day.

For many, the answer to how can one remain a fascist after the Holocaust was simply denial. Denial of the gas chambers. Denial of mass murder. Denial of the six million dead.

As long as there have been reports of Nazi crimes, there have been people determined to undermine them. The Nazis themselves were the first deniers, seeking to destroy the evidence of their crimes and hide them from the world.

However, shockingly, beyond the Nazis themselves, this book reveals a sad and unexpected truth; Holocaust denial, as we understand it today, actually started in Britain.

For most people, the notion that the Holocaust was an enormous hoax is nonsensical. How is it possible to see the newsreels from barbed wire encircled camps with emaciated and withered bodies in piles or mass graves and not be filled with horror and sympathy? With such definitive evidence how can one still not believe?

For those British fascists who truly believed that the genocide of the Jews had not occurred, one must look at their existing views about Jews. Many fervently believed in the idea of a ‘Jewish World Conspiracy’ — a clandestine cabal of powerful Jews, exploiting their position as a diaspora and their supposed domination of the world’s press and financial systems, manipulated world events, with the aim of creating a world government.

So, when reacting to the news of mass Jewish extermination at the hands of the Nazis, fervent antisemites were faced with the paradoxical situation whereby an all-powerful race had “allowed” itself to be destroyed. For many on Britain’s far right, the options for surmounting this logical contradiction were stark; either Jews were not all-powerful and did not rule the world or they had not been destroyed and the Holocaust was a lie.

Who was the first person to maliciously deny Nazi war crimes? Historians of Holocaust denial have picked out various candidates.

Deborah Lipstadt, in her book Denying the Holocaust, pointed to the prominent French fascist Maurice Bardèche. Others have identified his compatriot, Paul Rassinier who, despite having been a camp inmate himself at Buchenwald, later talked about the “myth of the Holocaust”.

Other scholars have argued that denial emerged from 1944 onward, produced by exiled Nazis hiding in Sweden, Arab states and South America, or that its earliest propagators were far-right isolationists and antisemites in America. Some even highlight the role of Allied information strategy during the Second World War which downplayed Jewish suffering.

While there is no solid consensus among historians as to who was the first true Holocaust denier, all accounts do have a commonality, namely they either ignore, overlook or downplay the role of early British Holocaust deniers.

In Britain, as elsewhere, the denial of Nazi crimes predated the war and can be found throughout the 1930s and during the war years. However, as the war progressed and increasingly solid evidence emerged of Nazi atrocities, elements of the British far-right were quick to challenge their authenticity.

One such example was the 1942 pamphlet Propaganda for Proper Geese, written by the Duke of Bedford, a leading far-right activist of the period. In it, he questioned the validity of the emerging stories about Nazi atrocities and brazenly dismissed the pictorial evidence as fake.

Another early contribution was Alexander Ratcliffe’s The Truth about the Jews, published in 1943, and a series of articles in his newspaper Protestant Vanguard in 1945. Ratcliffe, a militant Protestant and founder of the Scottish Protestant League, was a religious fundamentalist and extreme antisemite. He went as far as to make the remarkable claim that, “There is not a single authentic case on record of a single Jew having been massacred or unlawfully put to death under the Hitler regime.” His claim that the pictorial evidence of Nazi atrocities was being faked refutes Lipstadt’s assertion that the first to do so was the French denier Maurice Bardèche. Unsurprisingly Ratcliffe’s claims were met with anger and derision by the JC, which described The Truth About the Jews as “the vilest antisemitic pamphlet yet produced in Britain, and it is pure – or rather impure – Streicher from beginning to end”.

Interestingly, despite many pointing to Bardèche as the first real Holocaust denier, his 1950 book, Nuremberg II ou les Faux Monnayeurs, made it abundantly clear that he was well aware of much of the earlier denial literature emanating from Britain. He talked of the Anglo-Saxon intellectuals and journalists who rose up against the supposed injustices of Nuremberg long before he did.

Another early Holocaust denier was the infamous leader of the British Union of Fascists, Oswald Mosley. His reaction to the Holocaust has been something of a debated topic in part because of Robert Skidelsky’s biography which significantly downplayed his postwar antisemitism.

In reality, Mosley was actually central to drawing up the blueprint of British Holocaust denial. He was quick to criticise the Nuremberg trials as “a zoo and a peep show for gloating joy of everything that is lowest in human or beast”. His defence of Nazi atrocities, usually written in speech marks, was multi-faceted.

While accepting the existence of some concentration camps, he denied the conscious mechanical extermination programme by suggesting the conditions in the camps “were largely produced by Allied bombing and consequent epidemics”. He stated definitively that “Buchenwald and Belsen are completely unproved” and that “Pictorial evidence proves nothing at all.” His final refuge was to argue that if the Holocaust did happen then Hitler knew nothing about it.

The arguments Mosley used to deny Nazi war crimes have been regurgitated ever since and form the bedrock of British Holocaust denial, which became a veritable cottage industry for Britain’s fascists.

Looking back at this under-studied period of British fascism reveals that far from it being a later phenomenon, one can find all of the key tenets of modern Holocaust denial in the early work of British antisemites, making it necessary to reposition Britain in the history of early Holocaust denial.

Sadly, it is now clear that the earliest examples of printed Holocaust denial emanated not from France or America but from right here in Britain.

‘British Fascism After the Holocaust: From the Birth of Denial to the Notting Hill Riots 1939-1958’ is out now on Routledge Books