Thriller writers are a competitive breed. Their task is too difficult willingly to acknowledge a debt to another – except in the case of one name: Eric Ambler. “The source on which we all draw,” wrote John Le Carré in uncharacteristically hushed tones. His rival Len Deighton struck a similar communal note, calling Ambler “the man who lit the way for us all”.

Eric Ambler’s seminal transformation of the spy thriller has been well-documented. Before his advent in the years straddling the Second World War, the genre had wrung whatever action it could from thinly-drawn plots and characters. Yet by the time The Spy Who Came in From the Cold was released in 1963, these books had become diaphanous puzzles of character, politics and morality. Once mere pulp entertainment, the espionage novel became a camera obscura for its era – thanks, in large part, to Eric Ambler.

Perhaps, he had a more nuanced political sensibility than his predecessors. Whereas they had been ruddy imperialists, he was of the Left. The resulting willingness to point up the covert influence of financial capital on global affairs – rather than simply that of state actors or crime syndicates – provides added dynamism to his plots. But the staying power of his books is not rooted in politics alone. Underpinning them is also a bottomless fascination with the individual’s scope for self-delusion. Hence in The Mask of Dimitrios – his most famous work – we meet the grotesque Mr Peters who, throughout his various careers in heroin dealing and extortion, speaks in terms of what he refers to as “the Higher Things”. His moral and physical decay is complete, yet he appears sincere in the belief that he is engaged with the greater causes of human life.

Nearly two decades later, Eric Ambler returned to the same theme, this time placing it centre stage. The Light of Day – written in 1962 – recounts the experiences of small-time Anglo-Egyptian hustler Arthur Simpson. Whereas the earlier books are narrated by honest men thrown into dishonest situations, here we are treated to a full first-person narrative by one of the most wretched and misguided individuals ever to walk the shores of the Eastern Mediterranean.

The result is a psychological sketch of brutal acuity, wrapped in a comic masterpiece.

Like Mr Peters before him, Arthur Simpson is a sensitive man who attracts a disproportionate degree of bad luck and injustice. His character has been formed at a small boarding school where he was “taught how to hate; and it was the cane that taught me”, giving him a pathological need for revenge. Having fraudulently sold an inherited business – “Mum was entirely responsible for the trouble I got into over that” – he turns to publishing magazines of a “literary nature”. This too shortly gets him arrested. “I would remind you,” as he frostily informs a Turkish police chief, “that books like Ulysses and Lady Chatterley’s Lover were also once considered to be pornographic or obscene”. Released from prison and deported to Egypt, he falsely denounces his business partner as a spy in return for a new passport. By the time we meet him, he is dragging his feet along the bottom of Athens society, turning tricks as a driver and tour guide.

His activities don’t progress very far along the arc of criminal ambition before meeting their match. Apprehended in the act of raiding his client’s hotel room, he is press-ganged into action on behalf of larger and sleeker forces. His one task is to cross an international border; a feat he attempts without a valid passport. “The whole thing became utterly disastrous,” he says, “certainly through no fault of my own”. Comprehensively exposed by the Turkish Secret Service, he is let back into the water as their newly-minted intelligence asset.

Forcing an unwilling man into a dual role which far exceeds his capabilities is at the very epicentre of Eric Ambler’s interests as a writer. Where The Light of Day differs from his other writing is that it also forces the reader into an unfamiliar role. Whereas it is easy to sympathise with the mild-mannered teachers and writers who provide the foils in his other books, how can we do the same with Arthur Simpson?

And yet, like Arthur himself, we are left with no choice; as his humanity is soon squeezed to the surface by the inhuman pressures of intelligence work. We follow his swings from hatred to an almost canine loyalty to his new masters; from depression at failure to euphoria when he uncovers something he considers relevant. We feel his bruising when – having committed the cardinal sin of an intelligence source and turned his mind to qualitative judgement – he is castigated instead of praised. We share the wincing humiliation when he overhears reference to himself from his better-groomed associates – and intuitively understand his longing for The Light of Day finally to fall on his life.

And so, in spite of everything, we are forced to stay the hand of judgement. Because the real amorality in Ambler is found not at the bottom of society but at the top; among those who set in motion the ineluctable processes of war and exploitation, knowing they will keep the gains and externalise the costs. His writing shows detailed research of the reality of heroin addiction or of internment in a labour camp. Here too is a reason he remains so popular: the Cold War may have come and gone but, as aircraft carriers again churn the seas and opioids fell people for legal profit, Ambler’s world is still our own.