NO THEME has preoccupied post-war British writers more than that of betrayal. It is arguable that Le Carre is our major post-war novelist and the figure of the spy is pervasive in the literature of our time. As in Le Carre's An Honourable Schoolboy, he is a metaphor for more general infidelities in an age that has seen the rapid loosening of marital and familial ties.
The figure of Kim Philby, in particular, continues to haunt the imagination. His extraordinary career has already been thoroughly documented, by the journalist Phillip Knightley and others, and most people are reasonably familiar with it in outline.
A convinced Marxist, he was recruited as a KGB agent while at Cambridge. He entered the British foreign service in 1941 and was first secretary at the British embassy in Washington from 1949 to 1951. After the defection to Moscow of Burgess and Maclean, his friendship with Burgess led to an investigation. Although nothing could be proved against him he was forced to resign. He went to the Middle East as Observer correspondent until he disappeared from Beirut in 1963, surfacing soon afterwards in Moscow as a KGB major-general and confirming that he had been the ''third man'' in the Burgess and Maclean case.
Despite the intense scrutiny of his life, he remains an enigmatic figure. He presented himself as a man of conviction with a seamless record of loyalty to his spymasters in Moscow. Yet his life may not be so easily explained.
Knightley has now edited and contributed an introduction to a book which throws up new skeins of complexity. It is by Genrikh Borovik, a Russian journalist, writer, and TV presenter who was given access to Philby, whom he extensively interviewed during his last years in Moscow before his death in 1988, and to his files in the KGB archive.
The major disclosure of the book is the degree to which Philby was distrusted by his KGB masters. They reciprocated loyalty with suspicion and lies. His first assignment was to spy on his own father. A second, approved by Stalin, was to assassinate Franco, a task for which he was laughably ill-equipped, and which he never attempted to carry out, though as Times correspondent covering the Spanish Civil War (replacing former Herald editor James Holburn), he had opportunities to do so, interviewing the generalissimo on several occasions.
Philby's London controller sent Moscow an explanation for the failure. Perhaps because this unfortunate man knew his own fate was sealed, he ventured to suggest that the mission itself had been ill-advised. There is a chilling passage from the KGB files in which the disposal of successive London controllers is noted:
MAR: real name, Reif. London controller 1934-36. German and Polish spy. Shot.
MAN: real name, Maly. German spy. Shot in 1938.
KAP: Gorsky. German spy. Shot.
These men, and many more, were victims of Stalin's terror. Then, after the German invasion of the Soviet Union, when Philby had been recruited to British intelligence, Moscow's characteristic paranoia forced it into a series of misjudgments. These led it to undervalue Philby and the rest of the Cambridge ring who had infiltrated British intelligence.
His Moscow masters became convinced that he was feeding them lies. They thought he had been allowed to enter the Secret Intelligence Service (SIS) with suspicious ease. Elena Modrzhinskaya, a desk officer assigned to analyse his file, was intelligent, dogmatic, and wrong.
She developed an impressive but flawed case against him: he had failed to assassinate Franco; his controllers had been shot as spies or had defected; he had failed to identify British agents working in the Soviet Union. He was lying ''in the most insolent manner''.
Knightley comments: ''In the great history of espionage she will go down as the Russian version of James Angleton, the American counter-intelligence officer whose paranoid suspicions about KGB penetration nearly destroyed the CIA.''
Moscow's greatest bungle was when it blew the cover of the man who might have become head of the SIS. The incident that ended Philby's usefulness was the flight of Burgess with Maclean.
Philby had tipped off Maclean that he was in danger. Burgess arranged the get-away and, contrary to Philby's understanding of what was to happen, went all the way with him to Moscow, where he remained, thus implicating Philby whose friendship with Burgess was well known.
Philby always denounced ''that bloody man Burgess'' for this misadventure and could not bring himself to blame the KGB. Maclean, by contrast, furiously condemned the KGB for having thrown him to the lions, and Borovik confirms that it was the KGB which kept Burgess in Moscow.
The Russians, though they eventually honoured Philby as a master spy and gave him a fat pension, harboured their doubts about him to the end. One veteran spymaster, Yuri (''Peter'') Modin, told Borovik after Philby's death that he could, after all, have been a double agent:
''I cannot rule out that with his charm, intelligence and ability to influence people, he mocked us and them, the KGB and the SIS -- feeling that he was above them all.''
''He lived his own third life?''
''If you like. And there's nothing surprising about that. After all, he had a wonderful sense of humour.''
Knightley believes that the story of Philby confirms a truth about what, in an earlier book, he called The Second Oldest Profession. The great Russian spy in Japan, Richard Sorge, for example, was consistently disbelieved by Stalin, who dismissed his warnings of the impending invasion by Germany.
''Most spying,'' Knightley concludes, ''is useless, because the better the information a spy produces, the less likely he is to be believed''. In espionage, and in life, the truth is the last thing people may want to hear.
The Philby Files, by Genrikh Borovik, edited and with an introduction by Phillip Knightley. Little, Brown; #18.99