Alan's talk will first describe the German Enigma machine used to encrypt military communications in WWII. Then how the UK's Bletchley Park cypher unit broke the codes and the machines they constructed to help do this. He will highlight Gordon Welchman's key contribution, often overshadowed by that of Alan Turing.

However, success brought problems: How to sort the "wheat from the chaff". Again, Welchman had the solution having predicted the problem many years earlier.

Alan will then cover Welchman's time in the USA where he worked on military communications systems. In 1982 he wrote a book about Bletchey Park, much to the furore of the National Security Agency and UK's GCHQ. He had a visit from the "men in black" and the publishers were advised to pulp copies. Welchman lost his security clearance.

Finally, Alan will describe how Welchman's techniques are in use to day and will be super-charged by Artificial Intelligence. The technology is probably being used now to monitor our internet communications!