My understanding is that the code intercepted for the raid that evening was ANGRIFF KORN, but at this time the code breakers at Bletchey Park did not know where “KORN” was and only found out later that it was the code word for Coventry. So Churchill did know there was an attack coming but did not know were it would be and naturally assumed that it would be another attack on London. Let me look around a bit and see what I can find.
You might start by looking at reply #16.
I didn’t know that. Guess I always assumed that the lads at Bletchley were reading all the Luftwaffe traffic. Must’ve been one horrific night for the folks in Coventry.