Blaming foreigners for all your own country's ills is hardly a uniquely British thing. IM (very cynical and possibly conspiratorial) O the key thing is to make things as bad as possible. If Brexit turns out to be largely neutral or only slightly disadvantageous for the UK then there will be a lot of people with the time, energy and inclination to complain bitterly and hold the government to account.
If, on the other hand, the post-Brexit situation is so calamitous that we end up in a state of national emergency then all political parties will have to "pull together for the national good" and any or all complainers will be portrayed as being unpatriotic and defeatist.
This is what I was reffering to. If the results of a policy are horrible then the prevailing opinion is to turn against the government that endorsed them. It worked that way in the USSR, after their disastrous policies ended in famines the government had to find scapegoats to 'punish'.
Brits? No, let's support these guys who threw us in misery even more.
It's a bit of a caricature, but you get my meaning.
But as I concede, my opinions are firmly in

territory
I wouldn't be so sure. The government did just about every mistake that could be imagined plus several others you'd need both schitzophrenia and be high on acid to be able to imagine at all. This was due to either levels of incompetence not seen since China '58-'62 or deliberate actions. If the baboon (B.J., you just have to love those initials) and others are not, in fact, utter morons but intelligent, well studied individuals then the most simple explanation is their actions are indeed deliberate.
At this point two scenarios emerge, the one you proposed here and my version where they're doing all of this in order to derail Brexit, including the variant where they aborted this scenario in favor of an actual Brexit. We agree that version is less probable than the one with the Dunkirk spirit.
It comes down to this - either the British cabinet really is composed of clowns and assorted circus animals who recieved honors from high-ranking universities, or else the people in charge give that apperance to hide a different agenda - either a diamond-hard Brexit or no Brexit at all.
It's not a tinfoil scenario at all, but one of the several not all that plausible scenarios. The thing is one of those implausible scenarios
is a close approximation of reality, because anything outside of them is firmly in the shape-shifting reptile territory.
McHrozni