In the summer of 2013, shortly after Edward Snowden’s revelations about the surveillance capabilities of the American National Security Agency (NSA) began to appear, I had a private conversation with a former cabinet minister about the implications of the leaks. At one stage, I mentioned to him a remark attributed to a prime architect of some of the NSA systems – that they had taken the US to “a keystroke away from totalitarianism”. The MP scoffed at the idea. What I needed to remember, he told me, in that superior tone that toffs adopt when speaking to their gardeners, was that the US and the UK were “mature democracies”. In such polities, the chances of anyone coming to power who might have the inclination to use such power for sinister purposes was, he said, zero.