At the top of the British electronic intelligence agency is the Government Communications Headquarters (GCHQ), a very public entity whose circular building can easily be found by any inquisitive soul prepared to drive just off the A40 in Cheltenham which is about two hours west of London. But due to the nature of its work it is also one of the most secretive of UK agencies, from which very little public information is released. With over a century of history behind it and with some truly groundbreaking inventions under its belt it is rumoured to maintain a clandestine technology museum that would rewrite a few history books and no doubt fascinate the Hackaday readership.

Perhaps the most famous of all its secrets was the wartime Colossus, the first all-electronic stored program digital computer, which took an unauthorised book in the 1970s to bring to public attention. Otherwise its historical artifacts have been tantalisingly out-of-reach, hinted at but never shown.

A temporary exhibition at the Science Museum in London then should be a must-visit for anyone with an interest in clandestine technology. Top Secret: From ciphers to cyber security occupies the basement gallery, and includes among other exhibits a fascinating selection of artifacts from the Government agency. On a trip to London I met up with a friend, and we went along to take a look.

Technology From Our Finest Hours

The first exhibition highlighted a fascinating aspect of World War I communications technology. In the trenches of the Western Front an intricate web of field telephone lines criss-crossed, and presented a easier evesdropping target than you might think. They used single-wire earth return and the enemy could use earth electrodes to sense their earth return currents.

The Fullerphone was built to defend against this It’s an ingenious telegraph that used a low-pass filter and electromechanical chopper to allow Morse code signalling with tiny currents that were so low as to be undetectable by the current sensing would-be interceptor.

When looking at the history of GCHQ it is inevitable that the path will lead to the WW2 codebreakers at Bletchley Park. There is the Enigma machine with an exploded view of a rotor, followed by a fully functional Enigma clone created by the prewar Polish codebreakers, and then a selection of exhibits dedicated to the vital work of the Poles who came to Bletchley to continue their work after the war had started. This echoes the sentiment of Bletchley’s prominent memorial to Polish codebreakers in acknowledging the importance of their work to the success of Allied codebreaking as a whole.

An exploded Enigma rotor

The Polish Enigma clone.

An original Bombe rotor.

A switch unit from an original Colossus.

Another genuine Colossus part.

The Lorenz cypher machine.

Part of the exhibit is dedicated to the Lorenz cypher, dubbed “Tunny” by the codebreakers. It is here that that we see the value of the GCHQ artifacts and get to lay eyes on some truly priceless relics.

Working with a captured German Lorenz machine, details of the cypher were pieced together, leading to the creation of Colossus. While we’re familiar with both the Bombe and with Colossus, it is only through replica units because the originals remained classified and were destroyed when they had outlived their usefulness.

GCHQ have loaned the Science Museum in London a genuine Bombe rotor, and a pair of original Colossus parts that appear to have at some point been turned into desk ornaments. Not even Bletchley Park themselves nor the National Museum Of Computing can match the importance of these artifacts, they are the Real Deal!

Cold War Tech At Its Chilliest: Suburban Spy Gear and Mechanical Cyphers

The Portland Spy Ring, exposed in 1961, was a spying network that passed Royal Navy secrets back to the Soviet Union. The news came with the revelation that its kingpins, a couple known as the Krogers, had been Soviet agents in deep cover as a respectable couple living in a suburban bungalow in a town just outside London. Learning that the People Next Door might be communist spies caused a sensation in the staid world of early-1960s Britain, and some of this gallery covers the public reaction to the case. Of technical interest are the Krogers’ radio transmitter and high-speed Morse sending unit, discovered concealed beneath their kitchen floor.

This exhibit includes a cross-section of encryption technology from the 1940s to the early 2000s in a series of glass cabinets. The existence of all of the machines on show have previously been classified, and in the case of the newest items though we are told their existence is no longer secret the technology they contain will remain so for a few more years.

5 UCO was a wartime one-time-pad encryption device.

Front panel detail of the 5UCO.

The Soviet electromechanical encryption machine.

The Delphi punched-card encryption amchine.

the THAMER encryption device we’re told still contains classified technology.

The Queen’s encrypted telephone and its key.

Some of the earlier mechanical cyphers in the Enigma mould are not unfamiliar, but in these cabinets is plenty of gear never before shown in public. Everything from a super-secret 1950s Soviet mechanical cypher machine obtained after the fall of Communism to the Queen’s personal telephone encryption token is on show, and it was here that my friend and I lingered the longest.

While examining in detail the largest exhibit, a wartime rack-sized one-time-pad encryption system which appeared to have the pad encoded upon a paper tape, we were approached by and had an in-depth technical conversation with a Science Museum staffer. Was he simply someone who shared our interest in and knowledge of historical technology or had we been sounded out by one of the spooks themselves? Probably the former, but the prospect made us laugh. (As it happens back in the ’90s in one of my tech-related spheres it was intimated to me that somebody with my skillset at the time would find ready employment as a civil servant in Cheltenham, but I took a look at the salary as against the cost of housing in the city and decided against it. I suspect I would not have been good at the whole secret thing anyway.)

The Sinister Side Of The Spooks

It’s fun to see this equipment, but also refreshing to see items that don’t paint a rosy picture of all intelligence operations. The exhibit also challenges the visitor think about the implications of surveillance and espionage.

On display is the tale of a 1980s political scandal when the existence of a huge covert budget unapproved by Parliament was revealed. Under the codename Zircon, these funds were allocated for a top-secret British spy satellite. The story was surfaced by the investigative journalist Duncan Campbell (who in 1976 had been the first to reveal publicly in a Time Out article the existence of GCHQ) when a British Aerospace press release accidentally let slip some details of the project. The whole affair concluded with Special branch raids upon Campbell and his associates, the offices of the BBC, and the Spectator newspaper.

The Good Guys in Cheltenham built up in the previous section of the museum are revealed as a cog in a machine that includes a far more sinister side. In an era when public access to information was much more tightly regulated than it is for us in the Internet age, this revelation rocked the Government to its core.

Educating The Public About Their Data

The theme continues by introducing us to the world of Big Data and the threat that it poses. This should not be news to most Hackaday readers, but the general public remain largely unaware of the implications of so much information about them being available. There is an interactive artwork that mines Twitter and produces a mass of thermal printouts, and a 19″ rack full of what look like RAID units that we are told came from a Facebook data centre. Bringing us right up to date we have a look at the implications of IoT devices, including the infamous Cayla doll which had an unsecured Bluetooth connection.

It is here that the irony of the Museum entrance comes into focus. Entry to the gallery is free, but ticketed. At the barrier they ask you for a name and an email address, an early reminder of Big Brother’s eye on you. Is Mailinator still a thing I wondered, (it turns out, they are) as I remarked to the museum staffer the implications of starting a GCHQ exhibition with a data slurp.

An odd juxtaposition is provided by evidence of the community of GCHQ staff, in case we have reduced them to a shadowy faceless mass. We learn that the agency has a Lego club, and in a slightly surreal exhibit to prove it there are Lego models of the GCHQ building (complete with a laser-etched crest in the reception area) pictured at the top of this article. Something tells us that the model’s layout will not reflect the real thing.

Also on display are laptop parts from an episode in which technicians from GCHQ oversaw the destruction of computer hardware at the Guardian newspaper’s offices that had at one time held the revelations of the whistleblower Edward Snowden. The action that was symbolic at best in terms of its efficacy in destroying the data itself.

Then as you walk out the gift shop, displayed next to the GCHQ hoodie is a quantity of dust in a lighted frame. When GCHQ really want to ensure data never sees the light of day, they grind the machine containing it to a fine powder.

This Top Secret exhibition is only temporary. A fascinating way to spend about an hour and a rare chance to see some of GCHQ’s historical collection, as you might expect there’s nothing too secret in it but what’s there is still worth a side trip for anyone nearby. It runs until the 23rd of February 2020 so there is plenty of time left in which to see it, and there is enough in the rest of the Science Museum to detain a curious Hackaday reader all day. If you are visiting London, go along.