In London, a unique artifact—a 110-year-old lemon—holds a place of prominence in an exhibition dedicated to the storied past of MI5, the United Kingdom’s domestic intelligence agency. This exhibition, hosted at Britain’s National Archives, offers a glimpse into the mysterious world of espionage through rare artifacts like miniature spy cameras, microdots hidden in a talcum powder tin, and a briefcase once used by Soviet spy Guy Burgess—all contributing to the narrative of an organization that is gradually becoming more transparent.
During a press preview, MI5 Director General Ken McCallum remarked on the contrast between the agency’s authentic work and its fictional depictions, citing characters like John le Carré’s George Smiley and Mick Herron’s unsystematic Jackson Lamb as examples. Despite the fiction often seeming far-fetched, the true tales within the exhibition echo themes of classic espionage thrillers.
One such story features the now-blackened lemon, integral in the conviction of German spy Karl Muller during World War I. This fruit, along with another in his possession, contained evidence of Muller’s espionage activities—its juice used to compose invisible-ink communications about British military operations. His fate was sealed when he faced a firing squad at the Tower of London in 1915. Amusingly, MI5 later masqueraded as Muller, tricked his German handlers into sending more funds, and bought a car with the money—the vehicle was aptly named “The Muller,” a purchase which led to a reprimand from the Treasury.
The exhibition features declassified materials from the National Archives, supplemented by contributions from a secret museum within Thames House, MI5’s London base. It traces the development of a covert entity founded in 1909 with just two officers as the Secret Service Bureau. Notable wartime achievements are highlighted, such as the successful deception during World War II, which fooled Nazi Germany about the Allied invasion’s location by turning captured agents into unwitting double agents.
However, the exhibition does not shy from MI5’s historic blunders, like the prolonged infiltration by the “Cambridge Spies,” whose betrayals delivered crucial intelligence to the Soviet Union from within the heart of British intelligence. Exhibits include confessions and documentation from prominent spy Kim Philby, who ultimately sought refuge in Moscow after years of denial.
The evolution of gender roles within the agency also features prominently, with insights from a 1945 report by senior spymaster Maxwell Knight, who challenged the stereotype that women were less discreet than men—acknowledging that indiscretions often involved male agents.
The exhibition confronts other shortcomings, such as underestimating the fascist threat in the 1930s and misdirecting significant resources toward spying on the small Communist Party of Great Britain. A key, used to access the party’s offices without a break-in, symbolizes these efforts.
In more recent history, fewer items are exhibited from the past decades as MI5 shifted much of its focus from combating espionage to counterterrorism. Noteworthy is a mortar shell, a remnant from the Irish Republican Army’s 1991 attack on 10 Downing Street.
Though MI5 has disclosed records to the public since 1997, controls remain tight, with releases typically occurring 50 years post-event. Author Ben Macintyre, known for works like “Operation Mincemeat,” points out the significance of the exhibition, signaling a slow but profound shift towards transparency in a realm once shrouded in silence.
The exhibition “MI5: Official Secrets” is open to the public from this Saturday until September 28 and offers free admission, inviting visitors to delve into the captivating world of intelligence.