Once again life and death decisions hinge, ostensibly, on the information proffered by the respective espionage agencies of the US and UK. The JIC—Britain’s Joint Intelligence Committee—is confident that the Assad regime was responsible for chemical attacks, an assessment echoed, with “caveats,” by a report from America’s Office of the Director for National Intelligence. Caveats or not, the sexed-up WMD dossier gifted by Tony Blair to George W. Bush critically undermined the moral authority of secret intelligence, as well as tarnishing the hallowed “special relationship” shared by the two nations. But as historian Rhodri Jeffreys-Jones emphasizes in his timely new book, In Spies We Trust: The Story of Western Intelligence, the intelligence gatherers themselves did not significantly err in the lead up to 2003: the JIC rejected the idea that Saddam Hussein’s aluminum tubes were for enriching uranium, while Joseph Wilson told the CIA that Saddam’s rumored purchase of uranium “yellowcake” was improbable. What nonetheless transpired, writes Jeffreys-Jones, was “the subordination of the special British-American intelligence relationship to the special British-American diplomatic relationship.”

In his analysis, the Blair and Bush administrations both “politicized intelligence” by eschewing any separation of “estimative” and political processes—a trend exemplified by the career of Robert Gates, the longtime Director of Central Intelligence who went on to serve as Defense Secretary under both Bush and Obama (and was succeeded by then-CIA chief Leon Panetta). You could argue, of course, that distorting intelligence for political ends is hardly a 21st-century phenomenon: during World War II, British intelligence was responsible for various fabrications aimed at drumming up American support for intervention, sometimes virtually in cahoots with FDR’s government. But Jeffreys-Jones’ larger point is that the Anglo-American intelligence liaison, whose ascendancy and credibility were once unparalleled, has become “corrosive.” The complex history of that liaison is the subject of In Spies We Trust, an illuminating look at the two countries’ intelligence services in general, and more specifically at the century-old partnership between, on one side, organizations like MI6 and GCHQ, and on the other the CIA and FBI.

Studies of government espionage, even those by serious and “official” authors, are all too often awed by the glamour of spy-craft—Hollywoodized notions of poison tipped umbrella-toting villains ingeniously foiled by urbane multilingual heroes run deep—and reverently unquestioning of the established apocrypha. Jeffreys-Jones, however, explodes some foundational myths and considers the less appealing features of this world, including its historical, and sometimes disastrous, upper-class WASPiness. A tribal uniformity that took hold during World War I, when intelligence work mushroomed by necessity, it was perpetuated by the fact that, just as “Groton and Yale might propel you into the Department of State, so Eton and Balliol [College, Oxford] could be a passport into the Foreign Office.”

Such mutual class-based exclusivity meant an automatic affinity, argues Jeffreys-Jones, and fostered trust “rooted in shared values and in fashionable contemporary notions of ‘Anglo-Saxon’ racial and moral superiority.” Sneering at the French, for instance, was a common pastime. The early intelligence unit run from the State Department, created in 1915 and eventually named U1, was defined by Anglophilia and the prevailing belief that, despite professed American neutrality in the war, it was only natural to conspire with one’s own kind. Epitomizing this kind were diplomatic secretary Leland B. Harrison (Eton, Harvard) and his man at the US Embassy in London, Franklin D. Roosevelt’s friend and Harvard classmate Edward Bell, who often dashed off official memos on Racquet Club notepaper, crossing out the printed header and writing “department of state.”

British intelligence, meanwhile, sent Sir William Wiseman to run their US outpost. Wiseman, a mustachioed Cambridge dropout and heir to a baronetcy, assiduously cultivated his American counterparts and cemented a secret service partnership over club lunches with Gordon Auchincloss, a member of the new US intelligence elite and the son-in-law of Colonel House. Although it’s a still-debated suspicion that British intelligence tricked America into entering World War I, Jeffreys-Jones points out that “at the operational level, American and British intelligence officers would behave as if they were virtually indistinguishable.” Yet even Wiseman fell victim to the xenophobic insularity in which he’d formerly thrived: after the war, he was the subject of a flurry of correspondence between U1 officials, to whom it had alarmingly occurred that their English colleague might, with his vaguely Jewish-sounding name and banking career, be “a Yid,” who had “Semitic blue blood,” and was “a follower of the tribes of Israel.” In the end, Wiseman’s Burke’s Peerage entry was produced to prove his Gentile credentials.

For Britain, the biggest embarrassment stemming from the private school and Oxbridge stranglehold of intelligence remains the Cambridge Five double agent ring. In the 1930s, Kim Philby, Guy Burgess, Donald Maclean, Anthony Blunt, and a never confirmed fifth man were recruited as Soviet spies at Cambridge University. After effortlessly moving into high flying roles at MI5, MI6, and the Foreign Office, they passed secrets to the Soviet Union for decades. By 1951, Maclean was head of the American department of the Foreign Office, with access to the US Atomic Energy Commission. Philby, the most notorious of the group, became head of MI6’s Russian desk and was the CIA liaison in Washington. When US codebreakers intercepted messages that cast suspicion on Maclean and Burgess, who was also posted to the Washington Embassy, the Foreign Office sheltered them because, as Jeffreys-Jones puts it, “chaps like us can’t be traitors.” As for Philby, CIA counterintelligence chief James Jesus Angleton accused the Englishman of sabotaging the abortive 1949 Anglo-American invasion of communist Albania—the nations’ first joint covert endeavor in the Cold War—but his British employers dismissed the allegations, and he remained in MI6 for several more years. As a result, operational relations between MI6 and the CIA were “poisoned.”

So concluded the hey-day of transatlantic intelligence co-operation, an alliance that was invaluable during World War II, particularly in codebreaking. The countries had complementary strengths: MI6 made major strides in decrypts of German signals, while America developed expertise of Japanese codes. A US Army team presented a prototype Japanese codebreaking machine, PURPLE, to the staff at MI6’s secret cryptography HQ, Bletchley Park, in January 1941. (When they arrived at midnight, the woman who greeted them was unsure of the protocol: “I’d never met Americans before, except in the films. I just plied them with sherry.”) Still, Churchill was keen to retain an advantage with the superiority of his Government Code and Cypher School; having cracked the German ENIGMA machine, he was willing to hand over the information gained, but not the actual methodology, in the hope “that the USA would make concessions to British war aims and strategy, as the price of staying within the informational loop.” Eventually, after Pearl Harbor, there was fuller cryptographic cooperation, which helped assure Allied victory.

Even before entering the war, nominally neutral America was keen to financially invest in British spies: in the fall of 1941, US intelligence reportedly gave $100,000 to the Special Operations Executive, Churchill’s sabotage unit that sent agents into Nazi-occupied territories. US funds also swelled the coffers of the New York City-based British Security Coordination, which ran pro-British propaganda campaigns from an office in Rockefeller Center. In return, Britain trained fledgling US spies “in the arts of clandestine warfare.” As journalist Malcolm Muggeridge, MI6’s man in Mozambique, recalled: “They came among us, these aspiring American spymasters, like innocent girls from a finishing-school anxious to learn the seasoned demi-monde ways of old practitioners—in this case, the legendary British Secret Service.”

Such sentiments promote what has become an article of faith, upheld even by CIA historians: that the Agency sprang primarily from MI6 instruction. Those lauded British roots, contends Jeffreys-Jones, are in some ways mythical. In 1942 William Donovan, regarded as the father of the CIA, wanted to head a centralized organization that functioned “in peacetime as well as wartime.” Not entirely accurately, he pointed to Britain as the exemplar and inspiration—never mind that the US had a secret service tradition going back to the Civil War—and the British, naturally, encouraged the belief that their intelligence systems reigned supreme. No small part was played by Ian Fleming, who claimed to have drafted the charter for CIA precursor OSS (Office of Strategic Services), and whose James Bond books fed the fantasy of the archetypal English spy-hero.

Bond is still going strong but, in Jeffreys-Jones’ opinion, the same can’t be said for the two nations’ extra-close intelligence affiliation, a PR-damaged relic no longer appropriate in light of President Obama’s “pivot to the Pacific,” the decline of the north-east Ivy League influence, and America’s increasing racial and cultural diversity. Then there are new threats, like cyber warfare, which require a very different kind of response to that prompted by the Nazis and the Soviets. Europol, the Netherlands-based EU criminal intelligence network, has a dedicated cybercrime division, and the organization’s burgeoning importance since its founding in 1992 ought to weaken the UK’s reliance on its prestigious friends across the pond. Moreover, EU intelligence isn’t about “foolish adventurism,” writes Jeffreys-Jones, and cannot be “reined in at their convenience by the United States.” Not that Britain is ready to trust its Continental neighbors in all matters, even having been effectively demoted to a US sister-wife as Washington nurtures other intelligence relationships, such as with Israel—and even with France, whose intelligence backing and proposed partnership with the US over Syria may signal an unexpected new closeness. The Francophobe preppies of yesteryear will be spinning in their graves.

Yet recent events also seem designed to illustrate that Britain and America cannot quite be eclipsed in each other’s affections. Written before the Edward Snowden affair, In Spies We Trust recalls how, in 1976, a British journalist named Duncan Campbell was arrested under the Official Secrets Act: his Time Out article, co-authored with American journalist Mark Hosenball, had divulged that codebreaking institution GCHQ—Government Communications Headquarters, then a zealously-guarded state secret—conducted large scale illicit surveillance, of both friends and enemies, in tandem with the NSA. As Snowden’s leaks have revealed, the NSA and GCHQ continue their intimate association, with America paying the UK spy agency at least $100 million over the past three years “to secure access to and influence over Britain's intelligence gathering,” with the weaker regulations governing British spies a “selling point.” No wonder Obama pointedly characterized Britain as “our closest ally”, despite its refusal to back the US in military action against Syria. It seems like Jeffreys-Jones’ ultimate recommendation—the special intelligence relationship’s extinction—may not be fulfilled for a while.