At the time, some Leave campaigners thought the extension of the deadline for registering to vote in the referendum was a plot by David Cameron to increase the Remain vote. The Government gave people an extra two days to sign up after the voter-registration website crashed in the hours before the deadline.

Now Bernard Jenkin, the Leave-supporting chair of the Public Accounts Committee, says the site might have been hacked by the Russians or the Chinese. His committee of MPs found no evidence of such tampering, but said “we do not rule out the possibility that there was foreign interference”, while Jenkin told The Independent it would have been “entirely in character” for “the Russians and Chinese”.

This is purest baloney. The website crashed because lots of people left it to the last minute to register and whoever built the site failed to provide enough capacity for the surge, even though it was only slightly bigger than the one before the deadline for registering for the general election in 2015.

Cheney: Russian hacking could be 'act of war'

Nor, despite the paranoia of some Leavers, did the glitch have an appreciable effect on the vote. The extension and the publicity for it probably meant that more people applied to register than would otherwise have done: 430,000 during the extra two days. But most of those, as Professor Philip Cowley of Queen Mary University of London pointed out, would have found out that they were either ineligible or that they were already registered. Even if the Remain side might have secured a small net benefit from late registrations, Leave won the referendum by a margin of 1.3 million votes.

However, Jenkin and his committee have nevertheless performed a public service. Foreign hackers almost certainly had more interesting things to do than try to block a voter-registration website, and there might have been more effective ways to influence the outcome of the referendum, but they probably could have done it if they wanted to.

This is something that ministers and officials are worried about. The idea that the Russian or Chinese governments were behind this particular website crash is implausible, but Russian state-sponsored interference in western elections is something that probably did happen in last year’s US presidential election. Nothing as crude as bringing down websites, but US intelligence agencies concluded that the Russian government was behind the hacking and leaking of Democratic Party emails. Those leaks were damaging to Hillary Clinton’s campaign, suggesting a bit of sharp practice in the fight against her Democratic rival, Bernie Sanders, although whether they were damaging enough to swing the vote enough to change the result is impossible to judge.

I’m not sure Vladimir Putin considers British politics worth interfering in. Even if he could ensure the survival until the next election of a leader of the opposition who shares his view of Nato as a provocation to legitimate Russian interests, it's not as if that election would be poised on a knife edge, to be tipped over by the leak of an email from Number 10 being rude about Boris Johnson.

But protecting our democracy from outside interference, or even from malicious domestic threats, is part of a bigger and serious problem of cyber-security. Jenkin and the Public Accounts Committee are quite right to warn us how vulnerable we are.