Its probably as much to do with the British class system and the fact that the civil service was run by amateur chaps who knew chaps in the same club who had done classics at Oxbridge.

And now that the war was over all those gurls and those greasy engineers should go back to where they had come from.

Its also similar to the way in the last few months of the war career officers (proper chaps again) who had had a desk job where parachuted in to command positions to benefit thee post-war career