LONDON (NYTIMES) - John le Carre, whose nuanced, intricately plotted Cold War thrillers elevated the spy novel to high art by presenting Western and Soviet spies as morally compromised cogs in a rotten system full of treachery, betrayal and personal tragedy, died last Saturday in Cornwall, England.

He was 89. The cause was pneumonia, his publisher, Penguin Random House, said on Sunday.

Before le Carre published his best-selling 1963 novel The Spy Who Came In From The Cold, which Graham Greene called "the best spy story I have ever read", the fictional model for the modern British spy was Ian Fleming's James Bond - suave, urbane, devoted to queen and country.

Bond fed the myth of spying as a glamorous romp. Le Carre upended that notion with books that portrayed British intelligence operations as cesspools of ambiguity in which right and wrong are too close to call and in which it is rarely obvious whether the ends, even if the ends are clear, justify the means.

Led by his greatest creation, the plump, ill-dressed, unhappy, brilliant, relentless George Smiley, le Carre's spies are lonely, disillusioned men whose work is driven by budget troubles, bureaucratic power plays and the opaque machinations of politicians - men as likely to be betrayed by colleagues and lovers as by the enemy.

"Thematically, le Carre's true subject is not spying," Timothy Garton Ash wrote in The New Yorker in 1999. "It is the endlessly deceptive maze of human relations - the betrayal that is a kind of love, the lie that is a sort of truth, good men serving bad causes and bad men serving good."

Le Carre refused to allow his books to be entered for literary prizes. But many critics considered his works literature of the first rank.

"I think he has easily burst out of being a genre writer and will be remembered as perhaps the most significant novelist of the second half of the 20th century in Britain," author Ian McEwan told British newspaper The Telegraph in 2013, adding that he has "charted our decline and recorded the nature of our bureaucracies like no one else has".

Le Carre's experience as a British agent, along with his thorough field research as a writer, gave his novels the stamp of authority. But he used reality as a starting-off point to create an indelible fictional world.

In his books, the Secret Intelligence Service, otherwise known as MI6, was the "Circus", agents were "joes", operations involving seduction were "honeytraps" and agents deeply embedded inside the enemy were "moles", a word he is credited with bringing into wide use if not inventing it.

"As much as in Tolkien, Wodehouse, Chandler or even Jane Austen, this closed world is a whole world," critic Boyd Tonkin wrote in The Independent. "Via the British 'Circus' and its Soviet counterpart, le Carre created a laboratory of human nature, a test-track where the innate fractures of the heart and mind could be driven to destruction."

Born David John Moore Cornwell in Poole, Dorset, on Oct 19, 1931, he had a childhood dominated by his father Ronald, an amoral, flamboyant, silver-tongued con man who palled around with celebrities and crooks, left trails of unpaid bills wherever he went and was forever on the verge of carrying out a huge scam or going to jail.

Le Carre's mother, Olive (Glassey) Cornwell, walked out of the family house and into the arms of another man when he was five.

As crooked as he was, Ronnie Cornwell craved establishment respectability for his children and le Carre was sent to prep school, then to Sherborne, a boarding school, which he hated so much, he decamped for Switzerland at age 16 and enrolled at the University of Bern to study modern languages.

There, he was recruited by a British spy working undercover at the embassy, and so his life of spying began. Except for two years when he taught at Eton, England's premier secondary school, le Carre was a spy of some kind for 16 years, for MI6 and its domestic counterpart, MI5.

It was not until years later that he owned up to his earlier profession and he was always vague on the details.

But while a student at Oxford, where he went after Bern, le Carre kept an eye out for possible Soviet sympathisers in left-wing groups. In 1960, he moved to Germany, posing as a British diplomat.

Briefly, he led a triple life - diplomat, spy, novelist, writing his first book, Call For The Dead (1961), in red notebooks. The story of the unveiling of an East German spy operation, it was notable mostly for the introduction of Smiley and his faithless wife, Ann.

Forbidden by his employers to write under his own name, he fixed on "John le Carre". Over the years, he gave various explanations for it, finally admitting he could not remember which, if any, were true.

The Spy Who Came In From The Cold, the author's third novel, was published to instant acclaim and worldwide bestsellerdom.

The success of the novel - and the fact that a British paper revealed its author's true identity - allowed le Carre in 1964 to quit his undercover work to write full time.

He produced book after book set against the Cold War backdrop, including The Looking Glass War (1965), the Karla Trilogy (1974 to 1979) and The Russia House (1989).

The women in le Carre's early books were often caricatures - the ingenue, the adulteress and the sexless crone. But he tried to address the lapse in later books such as The Constant Gardener (2001).

If le Carre painted his Cold War world in shades of grey, his post-911 books seemed increasingly black and white.

They had the familiar le Carre flourishes - chess games of plots, biting characterisations, the sense of weak and sometimes decent individuals caught up in situations they barely understood, in-depth on-location research that he compared to "a perfectly normal espionage operation - it's just good reporting".

But he became disillusioned with Britain and the United States after the 2003 invasion of Iraq and the war on terror and was particularly angry at reports of Western torture.

Le Carre's first marriage, to Ann Sharp, ended in divorce in 1971.

He married Valerie Jane Eustace, a book editor, in 1972. Their son, Nicholas, became a successful novelist too, writing under the name Nick Harkaway.

They both survive him, as do his three sons from his first marriage, Simon, Stephen and Timothy; 14 grandchildren and three great-grandchildren.