There was a book published some years ago called
Deceiving the Deceivers: Kim Philby, Donald Maclean, and Guy Burgess by S. J. Hamrick. "Basing his argument primarily on the Venona archive of broken Soviet codes released in 1995–1996 as well as on complementary Moscow and London sources, Hamrick refutes the myth of MI5’s identification of Maclean as a Soviet agent in the spring of 1951. British intelligence knew far earlier that Maclean was Moscow’s agent and concealed that knowledge in a 1949–1951 counterespionage operation that deceived Philby and Burgess. Hamrick also introduces compelling evidence of a 1949–1950 British disinformation initiative using Philby to mislead Moscow on Anglo-American retaliatory military capability in the event of Soviet aggression in Western Europe."
https://yalebooks.yale.edu/book/9780300191462/deceiving-deceivers Hamrick believes that Philby was a "fraudulently overblown legend"--overblown by himself of course but also by western intelligence agents:
" In light of what we now know or should know, by any sensible measure Philby's importance as a KGB agent has been preposterously exaggerated in the West. He has been credited with passing intelligence secrets he couldn't possibly have known or revealed even if he had known. His passivity in Washington from 1949 until 1951 makes many of those claims absurd. Yet his name is constantly invoked, whether in explaining the Albanian fiasco of 1949, General MacArthur's defeats in Korea in the autumn of 1950, the theft of atomic secrets, or failures in the Ukraine. If a war that suits politicians is usually the wrong war, the same is true of covert operations that do little more than gratify the vanity of recklessly irresponsible intelligence officers. When failure came, Philby was always lurking about to explain their losses. When another inexplicable failure occurred, he was always there..."
https://books.google.com/books?id=yybGuSBeujUC&pg=PA28
Some reviewers are skeptical of Hamrick:
"Drawing on the Venona archive of Soviet intelligence cables transmitted to and from Moscow during World War II, Hamrick meticulously takes aim at Philby’s reputation as a master spy. In reality, he argues, British intelligence was aware of Philby’s treachery well before two of Philby’s associates fled Britain in 1951, but elected to dupe the supposedly ingenious spy into acting as a pawn in a British counterintelligence gambit to discover a broader Soviet spy network...
"Proving this thesis, however, is tricky. Unlike Dornon, Philby took pains to cover his tracks. “No Czech sugar-beet harvesters or Polish pig farmers were drawn from their fields or sties to the lane to watch him clatter heroically past,” as Hamrick points out. Any attempt to discredit Philby’s myth — and that of the rest of the Cambridge Five: diplomat Donald Maclean, intelligence officers Guy Burgess and John Cairncross and royal insider Anthony Blunt — must therefore pick through the meager evidence with a fine-toothed comb. Readers with a tendency to skim might consider a heavy dose of Ritalin, or a stronger amphetamine, to get through certain sections of Hamrick’s book, particularly the passages on the 12 cables sent from the United States to Moscow in 1944 and 1945 that refer to a well-placed British spy with the codename Homer.
"As it turns out, Homer was actually the alias of Philby’s partner Maclean, and it is on Maclean that much of Hamrick’s argument rests. According to official reports, the British found out that Maclean was a Soviet spy only in April 1951, one month before Maclean and Burgess escaped England on a midnight boat to France and were shuttled to Moscow by Soviet secret service agents. Hamrick conjectures that British intelligence agents, thanks to the work of their own cryptographers, could have discovered that Maclean was working for the Soviets as early as the summer of 1948 — and then let him and his fellow spies continue their work without informing their U.S. intelligence counterparts.
"The motives that Hamrick offers as to why British secret agents might have kept such information from the United States, despite a signed agreement on intelligence exchange, are plausible enough. At the time, Britain was cooperating with the United States on the development of nuclear weapons technology and would doubtless not have wanted U.S. officials to know that Maclean, who had been given considerable access to documents related to the Manhattan Project during his stint at the British Embassy in Washington from 1944 to 1948, had passed on top-secret information to the Soviets.
“It is reasonable to assume that rather than fatally compromise the far more important negotiations with Washington on the exchange of nuclear weapons information vital to Britain’s plans for a nuclear deterrent — and those prospects were promising — Maclean would have been quietly moved to another post after the end of his Washington assignment in September while London silently considered its problem and pondered an equally silent resolution,” Hamrick rationalizes.
"Another reason why British intelligence might have allowed Maclean to continue operating as a double agent, Hamrick suggests, would have been to use his and his partners’ betrayal to feed disinformation back to the Soviets. Hamrick even pinpoints the man who would have organized such an operation — the wily Dick White, who led the Homer investigation from 1949 to 1951 as chief of MI5 counterintelligence, and in 1956 became head of MI6.
"Citing a cryptic, somewhat dubiously sourced passage from former MI6 employee Hugh Trevor-Roper’s short 1968 book on Philby, Hamrick states that White had suspected Philby of espionage since 1945, when would-be Soviet secret service defector Konstantin Volkov was nabbed by his own agency in Istanbul in a case assigned to Philby, and brought back to Moscow to be shot at the Lubyanka. White, Hamrick alleges, kept Maclean’s outing quiet in order to organize an elaborate counterintelligence operation, by which Maclean would be recalled to London to head up the American Department at the Foreign Office in London, Burgess dispatched to Washington and Philby deliberately fed disinformation.
"However enthusiastic, Hamrick’s case for Philby being Dick White’s dupe is not entirely convincing, based as it is on a string of speculations. Central to his argument is an offhand comment made in 1976 by General Edwin L. Sibert, an “experienced and respected U.S. army intelligence officer,” to writer Anthony Cave Brown, who later included it in two books about British intelligence operations. According to Cave Brown, Sibert said that Philby had been used in Washington “to pass fictitious information about the effectiveness of the Strategic Air Command and the size of the U.S. atomic arsenal at the time of the Korean War.”
"True? Hamrick seems to think so, noting that Sibert’s “background alone makes his comment worth serious consideration.” He also draws attention to — though never really follows up on — the suspicious circumstances that allowed Maclean, Burgess and Philby to escape without ever being brought to justice back home, and to Britain’s refusal to this day to admit and declassify information on its prior knowledge of Maclean’s spy work.
"But even if we accept the theory that Philby was turned into Dick White’s tool, Hamrick fails to take it that crucial step further — to explain how the revelation of a counterintelligence operation that likely produced few if any tangible results impacts our knowledge of Cold War history. It never becomes clear what Hamrick wants to establish beyond the clarification of some historical details, and in the end we are left with little more than the author’s disgust at the philandering, drunken Philby, whose legend as a master spy certainly owed as much to fiction as it did to fact.
"Hamrick convincingly debunks the myth of Philby’s audacious penetration of the CIA by methodically highlighting the impossibility of his supposedly immediate access to some of its most sensitive secrets. And he does a good job of downplaying the usefulness of the information that Philby might have obtained even if he had infiltrated the agency, pointing out that “an effective CIA colossus” did not yet exist in 1949 and 1950.
"One gets the impression, however, that Hamrick is resigned to the fact that, no matter how well founded his theories may be, Philby’s legend and notoriety are unlikely to crumble. As he himself acknowledges at the outset, “Celebrity’s name is all we know and all we remember.”"
https://www.veteranstodayarchives.com/2004/12/18/secret-agent-man-philby-did-he-dupe-the-brits/