The slogan that defined the Brexit referendum campaign has lost its appeal. “Take back control” was a powerful message in the summer of 2016. Today, the dream of sovereignty takes second place to voters’ demands for prosperity to be protected.

This helps to explain a modest, but sustained, shift in public opinion since the vote to leave the EU. A new survey, conducted by DeltaPoll, suggests that another vote today would produce almost exactly the opposite result to the verdict in June 2016: a 5 per cent majority for Remain, compared with a four-point lead for Leave two years ago.

Another question explains what is happening — and illuminates a dangerously large gulf between those in early or mid-career, and those who are in or close to retirement. The poll asked people which of two statements about the current Brexit negotiations comes closest to their view:

“It’s vital for jobs, investment and living standards here in the UK for us to continue to trade as freely with the EU as we do today, even if this limits our freedom to decide our own business and trading rules.”

Or:

“It’s vital that Britain regains the right to decide its own business and trading rules, even if this reduces our ability to trade freely with the EU and risks being bad for jobs, investment and living standards.”

Almost half responded that they wished to protect jobs and living standards at all costs, while 38 per cent regarded British sovereignty as the higher priority. Stripping out the “don’t knows”, the verdict is 56-44 per cent in favour of economic strength.

The generation gap on the direction Brexit should take is significant. Among voters who are under 55 — and therefore likely to be directly affected by the impact of Brexit on jobs and investment — the margin is almost two-to-one: 65 to 35 per cent. But the over-55s regard sovereignty as more important, by 59 to 41 per cent.

Some fervently claim that any attempt to reverse the 2016 referendum result would provoke anger from those who voted for Brexit. Perhaps we should also consider the danger that younger Remain voters could rebel against the threat to future prosperity in the pursuit of a sovereignty they consider of secondary importance.

There is another argument that we need to consider. It is that the polling question poses a false dichotomy: that Britain does not have to choose between prosperity and independence, for we can have both. The problem here is that hardly anyone outside the ranks of the most committed Brexiters seems to share this view.

Leaked assessments by the government suggest that full control of our trade could lop 8 per cent off Britain’s economic growth over 15 years. The Institute for Fiscal Studies reckons that both growth and the public finances would suffer: there would be no chance of the much vaunted £350m a week extra for the NHS. The CBI and Institute of Directors have also voiced their concerns.

Only this week, a delegation of business leaders from Europe’s biggest companies met with prime minister Theresa May to warn of the dangers of the persistent uncertainties over Britain’s future relationship with the EU.

That is not all. The most optimistic projections of the Brexiters assume free and frictionless trade with the rest of the EU, as well as new trade deals with the rest of the world. With each passing week, it becomes clear that the price of frictionless trade beyond December 2020 — the end of the “implementation” phase — will be a requirement for the UK to apply the current customs union and single market rules, or something very like them, at least for food, components and manufactured goods.

The prominent Brexit supporter Jacob Rees-Mogg has said this outcome would turn the UK into a “ vassal state”. For the great majority of those with much of their working lives ahead of them, better that than one that threatens future economic prospects for them and their families.

This article originally appeared on the Financial Times.