Even if at some late hour Brexit does not happen for some reason, we will still have seen the country vote for and parliament approve a measure which inflicts substantial harm on its citizens. Anyone who still thinks otherwise should go through this Demos report on the opportunities and risks that Brexit creates, and ask whether the ‘opportunities’ are in fact things that we could have done anyway. Yes Brexit may force us to train more doctors etc etc. The disadvantages of doing it after Brexit is that the government will be more strapped for cash. 
In truth there are precious few opportunities that Brexit will bring, and an awful lot of costs. Those of us of a certain age have got used to losing votes of one kind or another, but in the past you could generally point to some group or class that gained from our loss. What has happened over the last few years has been something quite different: a democracy voting for things that will make almost all of the people worse off, to satisfy the interests or ideology of a minuscule minority.  The lessons we should draw from Brexit involve understanding clearly how this could have happened so to ensure it never happens again.
The referendum result went the way it did because of a perfect storm of two groups who had become disenchanted with the way society was going, or the way it had treated them. The first group, often forgotten by the left, were social conservatives who could be quite well off but who had probably not been to university. The kind of people who would react to claims that the Conservatives under Cameron were moving to the right by shouting ‘Nonsense. What about gay marriage’. The second group, the ‘left behind’, were the working class in once proud industrial areas that had declined steadily for decades. They were people who said before the referendum: 'well it cannot get any worse, can it'.
The first group, because they were social conservatives, were naturally fearful of social change like immigration, although they were likely to live in areas that had seen little of it. The second group were more dependent on the state, and saw in the last few years their access to social provision steadily decline. Yet until recently neither group would have cared much about the EU either way, and certainly would not have been prepared to pay good money to leave it.
In John Major’s day the Brexiteers were a very small group who could best be described as an irritant. (John Major had a less kind word for them.) How did this group get to win a referendum? Crucially, they had allies in the owners of two key tabloid newspapers, the Mail and the Sun. Over a prolonged period these papers pushed two key ideas: that we were in some important sense ‘ruled by Brussels bureaucrats’, and that immigration was a threat to public services and wages. The first claim resonated with social conservatives, and the second with the left behind.
After John Major’s time in office, this alliance encouraged the opposition to use immigration as a stick with which to beat the Labour government. The Conservatives talked about the UK becoming a ‘foreign land’. Concern about immigration started rising well before the arrival of Polish immigrants. This in turn led to growing UKIP support. With the election of Cameron the pressure continued, and being the chancer he was he gave into the demand for a referendum, thinking both that it wouldn't happen (because he wouldn’t win an outright majority in 2015) and that he could win it.
The final part of the strategy was to associate immigration with the EU. The EU was not a major popular concern until 2016. But the tabloids were relentless in their anti-EU, anti-EU-immigrant propaganda before the referendum. The Leave campaign emphasised immigration (Turkey) and the public services (£350 million), and with ‘Project Fear’ neutralised Remain’s strong card. The bias obsessed broadcast media did nothing to expose these lies, treated academic knowledge on trade as just one opinion, and the polls showed the lies were believed.
Some have subsequently chosen to focus on the left behind group, and to suggest that they were both hard done by and their concerns about immigration deserve respect. Authors like Goodhart have suggested that the middle class social liberals that came to dominate the Labour party had little regard for this constituency. We can of course debate the successes and failures of the Labour party, but it seems this analysis misses the important point.
Those who voted Leave didn’t win. If they wanted immigration to quickly fall, it won’t. If they ‘want their country back’, they will find that all the EU interference Brexiteers go on about amounts to little more than a load of bananas. If they think their wages will rise because of Brexit they will see - are seeing - the opposite. £350 million to the NHS will become £50 odd billion to the EU. Those that will be hurt most by loss of trade to the EU will not be in London, but the very areas that voted most strongly to leave.
In other words the big news is that Leave voters were conned. The only people who will gain from Brexit will be the tabloid owners whose power will be enhanced and the ideologues who for some reason think the EU was stopping them reaching their promised land. That, as I suggested at the beginning, is not something I have seen in UK politics in my lifetime. The parallels with Trump’s election are in this respect apt. We can no more 'reconcile' ourselves to Brexit as we can think that Trump is in any way presidential. If your takeaway from both events is that Labour should better represent the working class and Clinton was a poor candidate I would politely suggest you are missing something rather important.
If there is a lesson for the left in all this, it is to be smarter about what the hard right is doing, and not to play along by talking about British jobs for British workers. The main lessons are really for those in the centre and the soft right. Don’t appease those on the hard right by using migrants as a political weapon (a lesson that was once understood). Don’t appease them by offering them referendums. Don’t appease the right wing tabloids by trying to befriend their owners and protecting their backs. Don’t appease them by being unbiased between truth and lies. If you continue to do these things, have a look at the Republican party in the US to see what you and your country will become.
When Donald Tusk received the letter from Theresa May yesterday, he expressed regret that the UK was leaving and said ‘we already miss you’. The letter he received made clear threats to end cooperation over security if the UK did not get the deal it wants. This made me rather proud to be European, and rather ashamed at the actions of my country’s Prime Minister and her government.
 There are only two examples I can see where Brexit might be necessary before we can exploit the 'opportunity of Brexit'. The first is to enable us to reform a farming system large parts of which are heavily dependent on subsidies. People draw analogies with New Zealand decades ago. But any transformation will be both painful and may threaten things we take for granted in the UK, like sheep grazing grass hills in areas of outstanding natural beauty. (George Monbiot likes forests more than I do.) The second is to offer development enhancing trade deals, where of course I fully agree with my economics colleagues.
 I say the last few years because I believe it also applied to austerity, which people voted for in 2015 despite having endured its consequences during the previous 5 years.