The

The From the home of the co-breakers and the birthplace of modern computing, this is the Bletchley Park podcast.

Welcome to another Bletchley Park podcast Extra.

In the August edition, we brought you a rare interview with Sir Arthur Bonsal,

talking about his war work with the Government Code and Cipher School,

and giving us a peek behind the scenes at Churchill's most secret visit.

Now we can bring you an extended version,

which gives a fascinating insight into the work and atmosphere at BP during World War II.

So if you could start by telling me what your work here was about?

Yes.

The work I was concerned with in the German air section,

first of all, was the breaking of a broadcast information by the Germans about conditions at German airfields, whether they had got bad weather landing rules and force or clear, that kind of thing.

What they did, they set up this broadcast which was continuous, right to 4 hours throughout the war,

and which they listed each airfield that they either were using or might use for emergency landing,

that kind of thing, to say what the weather conditions were there.

And they indicated these,

which air, things they were talking about, by an encoded grid reference. They had a map grid

which was used throughout the German Air Force. A typical grid reference would consist of two

letters, which we call it a

bigram. That's not in the Oxford dictionary meaning, incidentally, a bygram followed by a number

of figures, three or more figures, depending how accurately they wanted to indicate the

position of whatever it was.

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