On January 7, 1961, a Canadian couple named Helen and Peter Kroger, owners of an antique bookshop in London, were arrested by British Secret Services at their bungalow in Ruislip, a sleepy suburb on the northwest edge of the city. They were part of Cold War Britain’s most infamous spy ring, passing secrets about the Royal Navy’s latest underwater weapons to the Soviets in Moscow. A search of the Kroger’s residence found encrypted documents hidden in a cigarette lighter; a transmitter that could send one-second blasts of Morse code; and, in typed correspondence, microdots of tiny text disguised as punctuation marks—periods!—readable only under a microscope.

These clandestine artifacts, on display in a recreation of the Kroger home that’s part of a new exhibition at London’s Science Museum, have never been revealed to the public before. “As far as I know,” says Dr. Elizabeth Bruton, the curator of “Top Secret: From Ciphers to Cyber Security,” “we’re the first U.K. museum to borrow them from MI5.”

Bruton and her team were approached by the British Government Communications Headquarters (GCHQ) with the idea of an exhibition that would mark its centenary. After passing security clearance, Bruton was given unprecedented access to GCHQ’s historic collections. She warns, however, “If there was something they weren’t able to lend, they wouldn’t have shown it to us.” Bruton did secure a 1937 Enigma machine, the device that Germany used to encrypt military messages during W.W. II (English mathematician Alan Turing was instrumental in cracking the code, thus enabling the British to read German orders). On view as well is the Queen’s personal encryption key for making private phone calls.

Another cabinet contains the remains of a laptop that stored the classified National Security Agency documents which whistle-blower Edward Snowden leaked to The Guardian in 2013. “[The Guardian] was ordered to destroy it by the British Government,” adds the curator. This section of the exhibition is preceded by the Orwellian warning that “The amount of data in the world grew ten times larger between 2016 and 2019.” Is GCHQ running a subliminal recruitment drive aimed at a new generation of digital spy?!

As for the Krogers, in 1969, as part of a secret-agent swap, they returned to Moscow where the Soviets gave them a heroes’ welcome—and issued postage stamps in their honor. —Harry Seymour