The damage becomes more palpable by the day. So, far from winning a £350m-a-week boost to the NHS, we find that the mere prospect of Brexit is costing the economy £800m a week.

And this is only the beginning, unless the madness can be stopped. I have pointed out before that her crucial contribution to setting up the single market was one of Margaret Thatcher’s finest achievements (the finest, according to Kenneth Clarke) and I say this as one who was not slow to criticise what I still regard as her originally misconceived approach towards British industry. That sado-monetarist period of the early 1980s was so disastrous that it provoked the chairman of ICI to go to Downing Street and ask the prime minister whether she wanted the company to remain in Britain. We now have present-day industrialists in a similar state of despair.

A crucial element in the Thatcher government’s economic recovery plan was the wooing of foreign investment, most notably Japanese, to these isles. The Japanese government and industrialists were given solemn assurances that the UK was a perfect location for their investment in the vast European market. Apart from providing jobs, the arrival of Japanese practices had a beneficent effect on British management and unions more generally.

We have now had, in quick succession, Nissan and Honda announcing relocation plans – sadly, from sites in Sunderland and Swindon where the majority voted Leave. I have visited Japan many times over the years, and still have good contacts there. From the moment David Cameron announced the referendum, senior Japanese officials smelled trouble. Frankly, they could not comprehend why a British prime minister would take such a risk, quite apart from the potential threat to what had been in effect an Anglo-Japanese accord that had worked well for decades.

Honda is being polite in downplaying fears about Brexit behind its decision, but the truest cause is pretty obvious. And now Lord Adonis, who as transport secretary negotiated major Hitachi investments here after the collapse of British train manufacturing in the 1980s and 90s, warns us in the New European that Hitachi too will feel betrayed.

I still hope that a second referendum will allow voters to have second thoughts, and young voters to have first thoughts

Which brings us to Cameron’s successor, Clarke’s “bloody difficult woman”, Theresa May. A case can be made that the crux of the crisis stems from May’s obsession with freedom of movement. Tories are supposed to believe in freedom, but not May.

When she inherited the office she had desired for most of her life, the prime minister, who was apparently concerned that the Tory party was the “nasty party”, wanted to do lots of good, socially beneficial things.

Instead, the nastiness has continued – social neglect is all around us – and she has been obsessed by opposition to the kind of free movement of labour that all but the most pig-headed Brexiters can see the British economy depends on. For this she was, and is, prepared to sacrifice membership of the customs union and the single market – apparently in an effort to keep the Conservative party together, an aim which looks increasingly doomed.

Someone who tried to instil sense into the prime minister’s approach was Sir Ivan Rogers, our former ambassador to the EU. He was eventually eased out, but is doing sterling work warning of the perils ahead. He was on scintillating form in front of the Lords select committee on the EU last Wednesday. In particular, he pointed to the absurdity of the British wanting “regulatory alignment” with a club the departure from which involves wilfully choosing regulatory disalignment.

In his book 9 Lessons in Brexit, Rogers says: “Virtually the entire British political class still thinks that its free-movement preoccupations are shared in the 27. They aren’t … among the other 27 member states, without exception, free movement is not at all the same business as external migration.”

He envisages five to 10 years ahead of hard lessons being learned. Me? I am still hoping that our elected representatives will vote to Remain and, if not, that a second referendum will allow voters to have second thoughts – and young voters to have first thoughts.

I like Dr Sarah Wollaston’s analogy with the patient who has signed up for serious surgery but changes his or her mind on being acquainted with new information about the risks. Surely we are being deluged with such information by the day?

William Keegan’s new book, Nine Crises – Fifty Years of Covering the British Economy From Devaluation To Brexit (Biteback), is out now. To order a copy go to guardianbookshop.com or call 0330 333 6846. Free UK p&p over £15, online orders only. Phone orders min p&p of £1.99