Robyn Williams: Now, did you know that my father was a part-time spy? Not a very good one in fact, unlike Mark Colvin's dad who was a top spook, often with GCHQ, the General Communications Headquarters with all those smart machines. Let's find out more.

I'm in the Science Museum in London in a very secret part of it. And are you allowed to tell me your name or is that off the record as well?

Elizabeth Bruton: My name is Dr Elizabeth Bruton, and I am the curator of technology and engineering at the Science Museum in London and curator of the Top Secret exhibition here.

Robyn Williams: Where did the idea for this exhibition come from?

Elizabeth Bruton: Well, the GCHQ worked with the Science Museum on the code breaker exhibition about Alan Turing in 2012. They lent some objects, and a few years later they were thinking about projects for their centenary and they approached the Science Museum about opening up their collections so that we would be able to put them on display and also making their staff available. So we've been working on it over the last 3+ years with particular focus on the last two years.

Robyn Williams: And you're a historian?

Elizabeth Bruton: Yes, historian of communications, intelligence and military history.

Robyn Williams: And they were willing to let their objects be seen by the public?

Elizabeth Bruton: Yes, anything that couldn't be put on public display they weren't going to show us, so I'm sure they have another store of objects that we will never get to see, but nonetheless we were able to put on display a number of objects that would not have been seen before. We have over 30 objects on display that have not been on public display before. We worked with other lenders as well, so we are the first UK museum to borrow from MI5, the domestic intelligence agency. We've also had objects which were declassified so they could be included in the exhibition.

Robyn Williams: Did Stella Rimington open the exhibition?

Elizabeth Bruton: No, she did not, I think she was busy that evening.

Robyn Williams: I can imagine. Okay, from where we are in the beginning, show me…I see a cipher machine over there. What have we got?

Elizabeth Bruton: So we have a number of cipher code and cipher systems on display. Our historic section where we are standing now deals with different historic episodes. But we are aware by doing that, that there were these rich and interesting code and cipher systems in GHCQ's historic collections that didn't quite fit into that episodic approach. So in the middle of the historic section we have what is essentially a timeline of the development of code and cipher machines in the age of telecommunications. So we have telegraph code books which were developed in haste in the middle of the Crimean War in the mid-19th century to keep communications secure as the information was being sent from London out to Crimea. And we have an entire timeline through to a system called Thamer which is used for modern PCs, although not producing key material for it any more, it's still classified until 2030.

Robyn Williams: Where's Enigma?

Elizabeth Bruton: We have three Enigma machines on display. We have a civilian Enigma machine, which was purchased by Edward Travis, then deputy director of the Government Code and Cipher School in Berlin in 1926 when it was still being used for commercial traffic rather than German military traffic. We have a naval example from 1937, also on loan from GCHQ, in our Bletchley Park section. And thirdly, one of the rarest objects we have is an Enigma Double or an Enigma copy which was an Enigma machine basically reverse engineered by Polish cryptographers and mathematicians and they produced a design for this. They made less than 100 before and during the Second World War. Only two have survived, and we have one on display in this exhibition.

Robyn Williams: So did any of those machines give you the shivers?

Elizabeth Bruton: I would definitely say holding an Enigma machine for the very first time absolutely sent shivers down my spine. I never thought that I would actually get to hold and operate an Enigma machine in my lifetime, and so it was a genuinely heart-stopping moment of just sheer joy and excitement. And I really do hope that although we can't allow our visitors to operate, for historic and preservation reasons, we do hope that nonetheless that excitement and passion and just these really incredible stories behind these objects comes through for our visitors.

Robyn Williams: Apart from Alan Turing the mathematical genius, did you get a picture of what these codebreakers were like, their background? Some people suggest there were women who were bloody good at crosswords or poetry or classics who turned up.

Elizabeth Bruton: So we have a number of different people who worked at the Government Code and Cipher School, later GCHQ, represented throughout the exhibition, and indeed others who worked in the field of codes and ciphers. There were some women who worked at Bletchley Park. We have a rather wonderful photograph of Mavis Batey who was one of the rare female codebreakers. But we also have interviews with current members of GCHQ staff, two women and one man, quite representative of the increased diversity of the staff at GCHQ. And we also have some of the objects that they use to recruit staff today, quite different to the tap on the shoulder of your Oxbridge buddy and passing them the Daily Telegraph crossword. Now they have a proper website where you can submit an application to join GCHQ.

Robyn Williams: I wonder if they really did that. So legend has it.

Elizabeth Bruton: So one of the rarest objects, in fact the rarest object we have on display, is this object which looks about the size of a large domestic fridge, and it's called the 5 UCO system. It is not only the world's first electronic cipher machine, introduced in 1943, it was considered so top secret, it was believed that all examples had been destroyed, but as part of the research for this exhibition, GCHQ found one in their store, and we are the first museum to put it on display, and as far as we know it is the only surviving example. This was used to transmit Enigma decrypts, that's Ultra traffic, from the UK, the decrypts which would have been made at Bletchley Park, through to military commanders in the field.

The first step of revealing the communications of others is breaking into a code or cipher system, but then you need to be able to share that intelligence securely otherwise you will reveal that you've broken the system and it can be improved or updated or replaced. So this is the machine that kept Britain's Ultra traffic completely secure during the Second World War, and indeed it was used into the Cold War as well for NATO and British traffic.

Robyn Williams: Wow. Yes, I see what you mean by shivers. And a nice picture of Margaret Thatcher, how convenient!

Elizabeth Bruton: Yes, so we are standing in front of a display of secure telephones, from the rather iconic Secraphone which looks like a relatively normal black Bakelite desk telephone from the mid-20th century, but there are two notable differences. Firstly it doesn't have a dial on it, and secondly it has a rather gorgeous-looking green handset, and these were secret telephones which were used by Winston Churchill and indeed others to make secure telephone calls during the Second World War and afterwards. It wasn't particularly secure at the beginning of the war. We have a rather impressive privacy set next to it which looks like a slightly mysterious large black file folder of some kind but it was actually a valve-based system to invert the frequency which is actually very easy to uninvert.

At the bottom of the case we also have a briefcase. So the changing systems of secure telephones, it's now mobile and this was used by Margaret Thatcher in the 1980s when she was away from her office, and this particular example she used during the Falklands War, including to call up the Minister of Defence to discuss the changing rules of engagement during the Falklands War which led to the sinking of the General Belgrano. So a very iconic piece of communications equipment used by the then British Prime Minister.

Robyn Williams: If I look over there I can see two KGB officers in disguise making notes. Has this happened a lot?

Elizabeth Bruton: We do sometimes have people when I'm giving tours who come up to me and seem to know who I am and what I'm doing and make interesting suggestions for our events programs. So I have no doubt that a large number of GCHQ staff will be passing through this exhibition. We welcome all visitors to the exhibition, and we hope it does encourage some people to consider a career in maybe cyber security or just a more general interest in codes, ciphers, communications, how we keep our communications secure today and how we can all contribute to that.

Robyn Williams: Yes well, having said that about the KGB, there is a doormat and there it is in Russian, presumably a little Russian house or something.

Elizabeth Bruton: Almost. So the doormat reads 'Welcome' in Russian, and this is actually meant to represent a bungalow in Ruislip in North London, that well-known centre for spying. It's actually, for those who aren't familiar with Ruislip, it's considered a quite pedestrian North London suburb where nothing exciting happens, but it turns out it was the home of Helen and Peter Kroger. He was an antiquarian bookseller, she was a housewife, but actually they were both American communists who were spying on behalf of Soviet Russia in the UK in the late 1950s and early 1960s.

When they were arrested as part of the Portland Spy Ring, stealing naval secrets from Britain and communicating it back to Soviet Russia, their house was searched for nine days. And a lot of the objects that we have on display here were either used to conceal some of the spy craft that they had or were the spy craft themselves. So they had microdot readers where they could photograph a document and shrink it down to the size of a full stop, and communicate it back to Russia. They also had a powerful radio set that they could communicate, send and receive very short messages from Soviet Russia. And just a really fascinating aspect to Cold War secret communications and spy craft in the late '50s, early 1960s.

Robyn Williams: By coincidence there's just out a book by Frank Close from Oxford, he's a physicist, all about Klaus Fuchs who is very, very famous, one of the most successful spies who sent an awful lot of nuclear material to Moscow and got away with it.

Elizabeth Bruton: Yes, so they still don't know to this day what secrets they shared with Soviet Russia because two of the members of the spy ring worked at the Admiralty Underwater Research Establishment in Portland, hence the name Portland Spy Ring. And they are pretty sure that they were sending information related to Britain's nuclear submarine program. But beyond that they were taking documents out, photographing them and putting them back. So we may never know the secrets that they stole or the impact it had on the USSR or indeed the Cold War.

Robyn Williams: How clever. Now this, as we walk on, we can't do the whole exhibition, it's just too big. There's a part of Bletchley Park, how interesting. This is open in London until February, and then you move to Manchester, is that right?

Elizabeth Bruton: Yes, so it will be open in London until 23 February next year. Then it will be running in Manchester from October 2020 to February 2021.

Robyn Williams: And what's the interest, the public interest, the young people's interest? What do they come to look at and say to you about this?

Elizabeth Bruton: I think young people seem to really enjoy large bits of the exhibition, but in particular they are very enticed by our puzzle zone where we invite our visitors to get hands-on with some basic aspects to codes and ciphers, but also the personality traits needed to work in that area, to be a code maker or a code breaker or to work in cyber security, and just the science, technology, engineering and maths, what we call STEM, that underpins these, as well as the personality types of teamwork and persistence and pattern recognition. So we have puzzles designed for everyone, from preliterate children who are maybe two or three, through to adults and beyond, and quite frankly some of the puzzles I haven't tried because I know…I fear, maybe not 'I know', I fear I wouldn't be very good at them, even though I know the solution anyway!

We are standing next to what basically looks like a small empty pond filled with large amounts of paper material streaming from a series of machines that look a little bit like cash registers. This is actually an artwork called Murmur Study and young people find this especially engaging. The American artist Christopher Baker produced this and essentially what it does is searches publicly available Tweets and searches them for keywords that are representative of emotional content, like 'argh', 'eek', 'ooo', 'ah', and then it prints out a selection with a certain time delay and prints them out onto this mass of paper that flows down from the machines into this empty plastic area, if you will.

And I think a lot of us think about the electronic content and the way that we communicate today. We probably think about our communications either just going to a recipient or maybe just sort of going out into the ether in some kind of ephemeral way and disappearing into some digital abyss. But actually this shows that we can physically manifest digital content that we put out into the world, and hopefully to help people think about where their information goes, where it's been stored, who uses it, who misuses it, what commercial platforms are using this and have access to their information. People just like the tactile nature of the fact that they can pull out a piece of paper and look at the Tweets that are on it and read the thoughts that someone else shared with the world.

Robyn Williams: Purloined from the cloud in many ways. Sometimes I'm relieved I don't have a mobile phone or use this sort of thing. Finally, where shall we finish? Oh there's so much, it's beautiful. The balance between security and privacy, and here…

Elizabeth Bruton: This rather interesting object which looks a little bit like the weirdest mirror you've never seen or maybe some kind of artwork pattern that you're trying to guess what the image is is actually top secret classified electronic waste dust. That's a lot of words. Essentially when GCHQ have finished with their electronic equipment, they can't just throw it in the skip as you or I would do because people could access it, see what they are doing, or take data from it and what they are working on. So instead they have to grind it down to an incredibly fine dust. So we've taken some of that dust and we've put it in resin and mounted it in a circle of light. So it's really, really quite beautiful, but also represents the unknown. We don't know what's on that dust, it could be the telephone the receptionist uses or it could be the most top secret anti-counterterrorism work that they are working on. And we wanted this to represent the fact that although this exhibition shares more about GCHQ and the history of secret communications than has been done before, there are things we can't know, for reasons of national security and for other reasons, there are just stories we can't share. And we did want to acknowledge that this exhibition can't be complete. So this rather beautiful dust represents that. Every single microgram has to go back to GCHQ.

Robyn Williams: Amazing! Thank you very much. Everyone should come and see it.

Elizabeth Bruton: Thanks very much.

Robyn Williams: I was with Dr Elizabeth Bruton, the curator of technology and engineering at the great Science Museum in London, where the secrecy exhibition is on until February next year. And I mentioned that new book by Professor Frank Close of Oxford about that sensational spy Dr Klaus Fuchs whose subterfuge changed nuclear history. Well, you can hear Dr Close telling the astonishing story in Big Ideas, broadcast this week, and there online from RN. Frank Close on Big Ideas. Quite brilliant.