It is far from over for the Leave side. The received wisdom in Westminster is that the outers are all but finished, and that the only question now is how badly they will be thrashed. That’s nonsense. With four weeks left, and the Government now banned from deluging us with its taxpayer-financed propaganda under the purdah rules, anything remains possible.

But the Leave campaign faces an increasingly difficult dilemma: as a broad Left-Right independence coalition, whose members disagree on just about everything other than the need for self-governance, it is finding it tricky to articulate a strong macroeconomic case for Brexit.

This is becoming a major issue, especially for more prosperous, middle-class, centrist and Tory-leaning voters in London and across the country who are craving reassurance that it’s safe to vote for Brexit. Many Telegraph readers fall into this camp; and we all have friends, relatives and neighbours who are vacillating, wondering whether maybe – just maybe – there may be some truth to the endless supply of screaming, hysterical anti-Brexit reports.

As it happens, such studies are a farrago of nonsense, based on question-begging, unrealistic assumptions designed to lead to a pro-Remain conclusion. In some cases, especially the Treasury’s analysis of the short-term consequences of leaving, they are a scandalously unethical concoction of a kind eerily reminiscent of Tony Blair’s dodgy dossier prior to the Iraq War.

But the fact that they are flawed doesn’t mean that their arguments can be ignored. It is desperately important that the economic case for Brexit be made much more vigorously. It needs to be divided into two components: a takedown of the EU as an ultimately doomed, job-destroying, declining and mismanaged behemoth which stands no chance in an increasingly agile, globalised world; and the mapping out of a clear exit strategy, compatible with Leave’s objectives, that shows how we would maintain and enhance our openness to the world. The message must be clear: we would be better off out – in terms of jobs, wages and growth. The costs of leaving will be smaller than the benefits, and this would become evident within a few years of leaving.

The core assumption of the anti-Brexit economists is that leaving would erect damaging barriers to trade; the pro-Brexit side must take on and demolish these arguments. The good news is that it’s quite easy to do so. The Leave campaign’s long-term aim is to break away completely from the EU. But there is no doubt that, were we to vote Leave on June 23, the UK would seek to adopt, as an interim solution, a Norwegian-style relationship with the EU which ensures that we remain in the single market, giving us plenty of time to work out new arrangements with the rest of the world.

That is both the only realistic way we would quit the EU – the only model, that, plausibly, MPs would support as a cross-party compromise deal – and the best possible way for us to do it. The Norwegians would welcome us with open arms, as their own influence would be enhanced, and other EU nations would seek to join us. Such a deal would eliminate most of the costs of leaving, while delivering a hefty dose of benefits as a down payment.

As part of the European Free Trade Association, we would remain in the single market, complete with its Four Freedoms, while withdrawing from agricultural and fisheries policies, justice and home affairs and the customs union. The City wouldn’t lose access and virtually all of the anti-Brexit scare stories would be neutralised, which is presumably why that option was mysteriously absent from the Treasury’s ludicrous analysis of the short-term impact of Brexit.

We would save money: Norway’s net contribution per person is lower than Britain’s. We would have to follow fewer rules: Norway has adopted 1,369 out of 1,965 EU directives, and just 1,349 out of 7,720 EU regulations. So Norway has been forced to swallow just 28 per cent of the total “acquis communautaire”, against all of it for the UK.

Leaving the EU and joining EFTA would make us more, rather than less, influential. We have only a small share of the votes in Brussels and can thus easily be outvoted. But Norway, which has technically no votes, has regularly moulded key rules, including the Consumer Rights Directive.

The real reason why we – as a large and powerful economy – would have greater influence in EFTA than in the EU is that Brussels is increasingly not the place where big decisions take place. Rules are increasingly negotiated under the auspices of global bodies: automotive norms are determined by the World Forum for the Harmonisation of Vehicle Regulations; food standards are determined by Codex Alimentarius; naval rules are under the aegis of the International Maritime Organisation; and the crucial new banking regulations are being determined by the Financial Stability Board. These regulations are then passed down, with the odd gold-plating, by the EU. These global bodies proceed by consensus, not qualified majority; we are currently represented by the EU at these meetings. A Brexit would allow us to have a seat at these top tables, and thus to disintermediate Brussels.

We would also be able to sign free trade deals with countries such as China: the EU has proved incompetent at this task, partly because it needs the agreement of all 28 members. Norway has been far more successful; we would be even more so.
"The economic case for Brexit is remarkably strong. If Brexiteers want to reassure floating middle-class voters, it will need to be made again and again"

It is true that being outside of the customs union would require some additional bureaucratic form-filling for our exporters. But the government could help by earmarking some of our reduced contribution to the EU to helping these companies: for example, slashing corporation tax on all exporters to 10 per cent. It could do the same to compensate farmers were they to face any new barriers, and in any case consumers would benefit hugely from being able to buy cheaper food from all over the world.

The economic case for Brexit is remarkably strong. If Brexiteers want to reassure floating middle class voters, it will need to be made again and again, loudly and clearly, over the next four weeks.