The importance of Bletchley Park's role in the preparations for D-Day should never be underestimated and perhaps can't be overstated.

Peter, let's be basic about this. What was Bletchley Park's role in the run-up to D-Day?

It was a link between what the Germans in Madrid were sending to the Germans in Berlin,

about the false information we were giving them through our agents,

and we were intercepting that link from Madrid to Berlin, intercepting the message,

sent by Morse.

They were coming to Bletchley Park where they were being decrypted,

then sent back to London to MI6 and to theley Park where they were being decrypted, then sent back to London,

to MI6 and to the double cross, where they could assess how effective this false information

had been and what else they could do to either add to it or supplement it, to make sure, in fact,

they continued to make the Germans think the way we wanted them to think.

The acid test of the effectiveness of the false intelligence.

Richard, can you tell us a bit about what we've got on show now

in Secrets Revealed, Introducing Bletchley Park, that tells the D-Day story?

Expanding on what Peter's just said, one of the most important things we've got in there

is one of the volumes that contains intercepted advert messages. That shows the information that Madrid were sending to Berlin and in turn

Berlin were sending to Madrid. And this allowed Bletchley Park to feed the information onto

MI6, who as Peter said, could inform their decisions about how effective the false information

they were sending to the Germans was. A good way of humanising this.

A good example is the double agent Garbo.

Now, he wouldn't have even known that Bletchley Park existed, would he?

No double agents knew of Bletchley Park.

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