Margaret Blyth was a cryptographer at Bletchley Park, the legendary home of the British Government Code and Cypher School (GC&CS, now known as GCHQ and located in Cheltenham). She was a Typex operator. The Typex was a cipher machine similar to the famous Enigma machine.
In 1937, when war with Germany began to seem likely, the British Government increased their preparations for the coming conflagration. The Chief of MI6, Admiral Hugh Sinclair, ordered GC&CS to expand its staff numbers. Those to be recruited were to be professorial types, drawn from Oxford and Cambridge universities.
However, as the cryptanalytic work became increasingly mechanized, many more staff were needed. As with many other industries, women were employed with some reluctance and only when circumstances forced the hand of managers.
Women were first brought into Bletchley Park after being approached at university or because of trusted family connections. Amazingly, debutantes were especially sought after as they were thought more trustworthy on account of their upper class backgrounds (thinking which now appears laughable after the scandals of the Cambridge spies, George Blake, and many others).
Still the recruitment needs of GC & CS grew. Women who were expert linguists and mathematicians were brought on board. Even the ability to solve crosswords was deemed proof of competence. In 1942, the Daily Telegraph ran a competition to see who could solve a cryptic crossword inside 12 minutes. The winners were deemed to have good lateral thinking skills, an important skill for cryptographers and codebreakers. The winners were thus approached by the military and invited to work at Bletchley Park.
By the end of 1944, over 2,500 women were employed by GC&CS from the Women’s Royal Naval Service (Wrens); over 1,500 women from the Women’s Auxiliary Air Force (WAAFs) and approximately 400 came from the Auxiliary Territorial Service.
Margaret Blyth’s brother was Air Marshall Sir John Humphrey Edwardes-Jones, KCB, CBE, DFC, AFC, a senior Royal Air Force commander who conducted early testing of the Spitfire and during The Battle of Britain was a squadron commander. It was through his work as Aide-de-Camp to Sir John that Alan Pollock met many of ‘The Few’, and was later inspired to undertake this project.
Her brother, Harold Blyth, was a Secret Intelligence Service (SIS) handler and ran the Danish double agent Ib Riis, who fed false information back to the Abwehr, the German military intelligence service.
Going down on the night train from Glasgow, which was absolutely packed with Service personnel, we arrived at Bletchley completely exhausted. From the station we were taken by transport to Bletchley Park only a few minutes away. The transport stopped at a very high security-fenced entrance manned by security guards and we were taken, a few at a time, into a concrete building where we were issued with a security pass and ordered to guard these with our lives. Without this pass we would be unable to enter the compound.
Before us was a large Victorian mansion with a sward of grass in front of it. A Wren officer escorted us into a low building adjacent to the mansion, where she gave us a very intimidating lecture about the extreme secrecy of both the place Bletchley Park and every aspect of the work which was done there.
We were never to divulge any information about our work; the place where we worked; never to discuss our work when outside, not even with those with whom we worked; we were not to ask anyone else on the site outside of our own unit what they did; and were not to keep diaries. Our category we were told was PV Special Duties X. We would wear no category badges and if anyone asked us what we did we were to say we were writers and did secretarial work. We would get no posting anywhere else as the work was too secret for us to be released.
Everyone had to sign a document, the Official Secrets Act, and we were told that if we divulged any information gained about our work we would be sent to prison, at least. So effective was this talk that when we left the building where we worked we just dropped a shutter and blanked it all out.