After leaving the RAF I joined GCHQ as a trainee Radio Officer at Bletchley Park. The man in charge (PSRO or Principal Station Radio Officer, now Grade 7) stood by the signing-in book and watched as we all "signed in". One chap had a particularly florid signature and the PSRO remarked "I see that you are leaving us Mr X." When Mr X gave him puzzled look the PSRO said "You appear to have crossed out your name."
That particular PSRO had been at Bletchley Park for many years and insisted that typewriters should NOT be used when taking down Morse code. Came the day when he retired and on the following morning an HMSO lorry drew up with a cargo of Imperial typewriters...
A similar sort of chap was the Senior Technical Officer (STO, another grade 7) who had been in post for many, many years and was very critical of the students despite being somewhat out of touch. He was particularly scathing when one group had an exercise to create a requirement for a new oscilloscope; he said "You'll never get an instrument with such a short rise time, etc, etc." Fortunately one of the students had friends in the oscilloscope industry and next day produced publicity leaflets for the latest oscilloscope with parameters that far exceeded those in the requirement. STO retreated, mumbling, into his office.