The word “Quisling” has re-entered political debate. Peter Oborne is perhaps the most eminent commentator to have reached for it, in a recent tweet where he declared:

“Boris unprincipled? What about the Cameron Quislings – cabinet eurosceptics who support Remain.”

Oborne added a link to his denunciation in the Daily Mail of those ministers for betraying their principles in order to promote their careers. But generally speaking, we hear less of Quislings that once we did.

When Oborne and I were young (he was born in 1957, I in 1958) anyone who showed signs of getting a bit dictatorial would be called, perhaps half in jest, Hitler, a propagandist of any kind would be referred to as Goebbels, and a traitor was almost certain to be described as a Quisling. But when I asked an intelligent teenager what this last term means, she hazarded: “Someone who gets quizzed?”

Vidkun Quisling, who on 9th April 1940 helped the Nazis to invade Norway and with Hitler’s encouragement mounted a coup d’état against the legitimate Norwegian government, immediately became a synonym for the most vile and unpardonable treachery. On 19th April 1940 The Times published a leader under the headline “Quislings everywhere” in which it said:

“To writers, the word Quisling is a gift from the gods. If they had been ordered to invent a new word for traitor… they could hardly have hit upon a more brilliant combination of letters. Aurally it contrives to suggest something at once slippery and tortuous.”

The Daily Mail quickly picked up the usage, so did the BBC World Service, and so too did Winston Churchill, who on 21st June 1941 declared:

“A vile race of Quislings—to use a new word which will carry the scorn of mankind down the centuries—is hired to fawn upon the conqueror, to collaborate in his designs and to enforce his rule upon their fellow countrymen while grovelling low themselves.”

Quisling had become the most infamous of all Norwegians. His countrymen, who were overwhelmingly pro-British rather than pro-Nazi, regarded this collaborationist puppet with detestation, and so did people around the globe.

Yet Quisling believed himself to be a patriot, who was doing his best for his country in difficult circumstances. He was so dangerous because he possessed, along with great ability, a kind of blinkered and misguided moral seriousness, which enabled him to convince himself, right up to the moment when he was executed by firing squad on 24th October 1945 after being convicted in a Norwegian court of treason, that he was innocent.

His impenitence makes him in some ways an even more objectionable figure. His obstinacy and moral vanity were such that he believed himself to be dying “a martyr’s death”.

But his career also suggests how a gifted man could be seduced by fascism. Vidkun Quisling was born in 1887, the son of a country pastor who had married a ship-owner’s daughter. At school, the boy was considered a genius by his contemporaries, and in 1908, when he passed out from the Military Academy, he obtained the best marks of any cadet since that institution’s foundation in 1817.

The young Quisling was a brilliant staff officer, who could attain a swift and complete grasp of the facts, or what he took to be the facts, in any given situation, and bring order out of chaos. As his biographer Hans Frederik Dahl observes, “Throughout his life, he believed that anything was possible provided there was a good plan that had been elaborated in a Staff headquarters.”

Norway managed to keep out of the First World War, but Quisling specialised in the study of Russia, and in 1918 was sent to St Petersburg as Norwegian military attaché, where he soon realised how formidable the Bolsheviks were. A few years later, Quisling was recruited by Fridtjof Nansen, the celebrated Norwegian explorer and humanitarian, to help with famine relief in the Ukraine.

Unlike many foreigners, Quisling understood the catastrophe which was taking place in the Russian countryside, and in Dahl’s words, he proved himself “an unusually altruistic, efficient and tolerant aid worker”. He was exceptionally shy with women, but married a 17-year-old Ukrainian woman who “fulfilled his need to play the role of rescuer”, after which he fell in love with a second Ukrainian, Maria, to whom he remained married for the rest of his life. They attempted to pass off her predecessor as their foster daughter.

Towards the end of the 1920s, Quisling served as a Norwegian diplomat in Moscow, where he also helped to represent British interests, for which he was awarded a CBE (removed from him in 1940). But at this point he returned to Norway, and set up a new, fascist, political party called the NS, or Nasjonal Samling. His leadership was marred by a kind of humourless naivety, and by a propensity to get implicated in scandals, so although he served briefly as Defence Minister, the NS was soundly defeated in the elections of 1933, after which it failed even more dismally in the elections of 1936.

Quisling had identified Bolshevism as a menace to western civilisation, and had become convinced that liberalism was no better. Both, he decided, were malign Jewish inventions. From 1935, under German influence, he became markedly anti-Semitic, though there were few Jews in Norway.

When war came, he feared Norway would end up like Poland: a battleground to be fought over by the Germans, the Russians and the British too. His own cultural preferences were, as was often the case in Norway, for Britain: English was his best foreign language, each day he would read The Times, and there were more English than German, French or Russian volumes in his library.

But his racial views brought him closer to Germany, seen by him as the power which could lead a united Europe in the battle to retrieve Russia from Bolshevik barbarism. In December 1939 he visited Berlin and contrived to meet Hitler, who realised he might be useful when Germany seized Norway.

By this point, wishful thinking had obscured Quisling’s ability to see straight. One of his old friends said “Vidkun has gone stark raving mad”, while another found him babbling in an Oslo patisserie about the apocalypse. Quisling had elaborated a personal philosophy which he called Universism, drawing on Christianity and modern physics.

He believed that if he helped Hitler take over Norway, Hitler would in turn help Norway to remain independent. Only the first part of this implausible bargain was kept. Quisling led the collaborationist Norwegian government, and urged Hitler (somewhat superfluously) to invade Russia, after which he quite correctly informed the Führer that the invasion would only succeed if the many peoples subjugated by the Bolsheviks were mobilised against Moscow, not turned into Nazi vassals.

The Norwegian staff officer had arrived at an accurate analysis of the situation, except he completely failed to understand that Hitler was never prepared to treat conquered people as equals. Quisling strove for Norwegian independence, but Hitler strung him along by saying this question could only be addressed once victory had been attained.

When I started reading Dahl’s biography of Quisling, I hoped, with heartless frivolity, that there might be some black humour to be derived from it, and even a provocative reassessment to be offered. But the story is far sadder than that. By siding with the Nazis in April 1940, Quisling had committed an irretrievable blunder. This clever and sincere fool remained loyal to them, and under their thumb, until the bitter end in May 1945, and even then he was unable to repent.

He had accepted the execution of members of the Norwegian resistance, and a third of Norway’s 2,173 Jews had perished in Auschwitz. It is impossible, when one knows a bit more about him, to think of him without a shudder, or to place any present-day British politician in the same category.