1943.

How do they fit into this story? They arrive in August, and the radio intelligence company has been established a few months earlier.

So it's still in its fairly early days, but it's all set up in Voxmoor.

And so it's a natural place for Brzezinski and Zhigalski to be sent.

They arrive and they join the exploitation platoon, which was the code-breaking setup.

And one of the people who's come over with them is Lieutenant Shakhno, who takes over running the exploitation platoon.

So the various people who've come with Brzezinski and Zhigalski are folded into the operation of Boxmoor.

How was this resolved then? How does this story end, David?

I'm thinking here, for example, of Turing's proof, the famous Turing machine, and although this was a little bit later, the Turing pattern.

Well, the really important moment is in 1935 when, as a, as a fellow, he writes with Max Newman, who was at Cambridge at the time and was sort of his mentor in mathematics.

He started working onThe Entscheidungsproblem in German, which translates as the decidability problem.

And this is a concept in mathematics where the question is whether it is possible that all things in maths can be resolved, that you can write an algorithm that would, would give you the answer to any problem.

And some mathematicians had argued that actually maths is fundamentally unprovable on some levels.

There are some aspects of mathematics that while they appear to be true, you could never rigorously demonstrate them using logic.

And Turing addressed this problem in a paper called On Computable Numbers, which was published in 1936.

Can you describe the events that led to his conviction?