> I can tell you without fear of contradiction that this overused practice of 'leaking' was not common in the old days.<
I agree with what you say. I think that people were more compliant towards some aspects of authority, in past times. ( Though perhaps not quite so compliant as the example indicated in the book which Stanley Jenkins kindly mentioned. - The image of some solemn Official incancerating a crusty British crew in a room and ordering them all to sign-up to a lifetime of confidentiality... well, it has a certain amount of comedy value, but if anyone had really tried that, they'd have been lucky to have gotten out of there with their back teeth and their socks intact !)
In any event, the key point is that there hasn't been that kind of compliance for a long time. It isn't so much a case of 'authorised' leaks, sanctioned by politicians. It has more to do with the the increased level of 'unauthorised' leaks and the apparent ease of access to supposedly secure data. That's why I'm doubtful that there would be any startling revelations from the 1912 archives - official secrets, or otherwise. - (But, as I said before, I'd be happy to be proven wrong.)
regards Jim F.