Now, let me get this straight. We have a fissiparous, Brexit-supporting government, many of whose MPs are stepping down, convinced that their party is heading for its wilderness years. Correspondingly, we have a Labour opposition that is riding high in the polls, led by Keir Starmer, who – unlike his predecessor Jeremy Corbyn – played a noble part in the remain campaign and argued passionately for a second referendum.

Proponents of a second referendum hoped that the country would acknowledge its historic mistake, and return to the European Union it should never have left. I was one of them. We failed.

Since that failure, what we were worried would manifest itself has indeed manifested itself. Brexit is an economic disaster, with the Office for Budget Responsibility and National Institute of Social and Economic Research estimating the hit to the nation’s GDP at anything between 4% and 6%.

There are daily reports now of the bureaucratic disruption at customs to what was once the ordinary course of business for small and medium-sized firms. Exports and imports alike are affected. There are mounting supply chain shortages; costs are rising as a direct result of Brexit, with more disruption to come. Farmers who voted for Brexit now regret not having been more careful about what they wished for.

As for those famous trade deals, promised as substitutes for deals with our nearest and largest market, they have been replaced by – er, well, let’s face it, they have not been replaced. It’s pathetic: a national example of self-harm that makes us an international laughing stock.

But the disaster is not just about business, trade and the economy. It embraces people’s rights, privileges and opportunities – made possible, indeed taken for granted, via our membership of the EU. This is especially bad for the young, not least for the 60% of 18- to 24-year-olds who, surveys indicate, think leaving the EU was a mistake.

Defeatists tend to say that the EU would not want us back. Certainly they would want to deal with trustworthy people, which Boris Johnson and co were not. But they too are troubled by the consequences of Brexit – although, as I have said before, they know that what has happened to Britain has acted as a brake on potential leavers in the remaining EU nations.

But what happens when the EU offers an olive branch – a plan for 18- to 30-year-olds in all member countries and the UK to be able to work and study throughout the EU for up to four years? Rishi Sunak rejects it immediately, and Labour follows suit with all that guff about “red lines”.

Now, wait for it, the reductio ad absurdum of Labour’s position is this: we are told that it will fight the coming election on the Conservatives’ “economic failure”, not on Brexit. This is, I think, a classic example of what my philosopher friends term a “category mistake”. Brexit constitutes an integral part of this government’s economic failure. Highlighting that failure, and promising to reverse it, should be central to Labour’s strategy. The fact of the matter is that Starmer was right about Brexit, and the Brexiters who captured the Tory party were wrong.

I gather that there are rejoin candidates in the imminent local elections. It might strengthen Starmer’s arm if they do well.

It is a commonplace that the British economy is suffering from years of underinvestment, and that this has undoubtedly affected its productivity. There are too many international comparisons from which the UK emerges poorly. In part, the situation resembles the way that successive Conservative and Labour governments in the 1950s and 1960s were concerned about what was known as “relative decline” and decided that one way of dealing with this was to join what was then the Common Market.

Association agreements were not enough. We needed the full works. After several failed attempts, we entered the European Economic Community in 1973, and that evolved into the EU, with the added benefit of the formation of the internal – single – market, in whose formation we played a crucial role.

That gave a vital boost to our economic performance. Now, at a time when there are so many repair jobs to be addressed, but endless complaints about the cost, UK plc needs another boost, and what Keynes called the “animal spirits” of entrepreneurs require a shot in the arm.

In my view, a more confident Starmer could provide that if he ceased being mesmerised by “red wall” Brexiters and returned to first principles. Most people now regard Brexit as a serious mistake. Re-entry would be good for investment – and for growth and tax revenue.

As the former Bank of England governor Mark Carney puts it: “‘Take back control’ was actually code for ‘tear down your future.’”