Bletchley Park and the RAF Y Service: Some Recollections

The RAF Y Service and the German Air Section at Bletchley Park collaborated in producing a great deal of intelligence about GAF (German Air Force) operations in World War II. However, two errors in pre-war planning reduced this output. The first error was the decision that the Government Code and Cypher School (GC&CS) should be responsible solely for cryptography, the interpretation of Sigint to be the task of the Intelligence recipients. The second was the general assumption that the information obtainable from intercepting the low-grade codes and plain language used in the control of Air operations would only be of intelligence interest while the operations were in progress. After-the-event study of these communications by the German Air Section produced unique information needed by the RAF Commands. The Air Ministry took an unduly long time to agree that this information should be provided to them.