The sarcasm and sneers following the resignation of Lord Frost were a reminder that the rancour that followed the referendum has yet to pass. He worked for the Scotch Whisky Association, retired mandarins laugh. He was hated by the Europeans, Remainers sigh. He was unpicking a treaty he himself had negotiated, commentators mock.

The jeers say more about the critics than their target. Before the 2019 election, Lord Frost and Boris Johnson found themselves trapped. They needed a Commons majority to sort out Brexit, but they could not win one without a withdrawal agreement, and they could not reach a sensible agreement with the Remainer-dominated Parliament they inherited.

They therefore agreed a deal they knew, deep down, could not hold. Northern Ireland would be treated differently to the rest of the UK, with European rules and regulations applying there to avoid a “hard border” with the Republic. A border, in effect, would exist between Northern Ireland and mainland Britain. At least, they were able to hope, the EU would tread gently, given the sensitivity of the creation of an internal border, the fragility of peace in Northern Ireland, and the understandable concern of Unionist politicians.

It was always probable, then, that the NI Protocol would need to be renegotiated. But what has happened since has made this unavoidable. The Protocol has not avoided economic disruption in Northern Ireland, nor has it protected the position of the province within the United Kingdom. Two-hundred British companies have stopped supplying the NI market, supermarkets have reduced product lines, and delivery costs have gone up.

Despite its high-minded rhetoric about the peace process and support for the Good Friday Agreement, the EU has acted in bad faith throughout. European border checks in Northern Ireland represent 20 per cent of all checks across the whole EU external border. There are more checks in Northern Ireland than in any member state, even though its 1.8 million people are the equivalent of 0.5 per cent of the EU population. And, of course, earlier this year the EU abruptly said it would suspend the Protocol to allow Brussels to impose a vaccine border between Northern Ireland and the Republic.

Lord Frost was leading the work to put the status of Northern Ireland right, and it is hard to avoid concluding that his resignation – officially about concerns over the Government’s “political direction” – was more specifically a response to compromises on the role of the European Court of Justice in Northern Ireland.

While Brussels has been willing to discuss reducing border checks and the authorisation of medicines in Northern Ireland, shortly before Frost’s resignation it became clear that Britain no longer saw the role of the European Court as a red line.

Unionists in Northern Ireland – concerned that their new constitutional status will become permanent – together with prominent Leave supporters in the Conservative Party are therefore right to be concerned by Frost’s departure. But some Tory radicals – free marketeers insistent that Brexit must mean a fundamental change in our economic model – have their response wrong.

“The whole point of Brexit,” one Tory MP wrote, “is radical supply-side reform.” In other words, it was only by leaving the European Union that Britain could shrink the state, radically deregulate its economy and cut taxes.

This is wrong for several reasons, most obviously because there is no democratic mandate for it. Leading Leave supporters might have spent the referendum fantasising about making Britain a “Singapore-on-Thames”, but most Leave voters wanted national sovereignty, democratic control and stronger solidarity between citizens. The referendum was won among voters protesting against the way the world economy had destroyed job security and killed wage growth. They were not voting for more of the same.

Brexit does require us to change, however, because standing still and doing what we did before, but on less preferential trading terms with Europe, will reduce growth and make us poorer than we would otherwise have been. And, of course, economies always need to change: in response to new technologies, trade patterns, competition for scarce resources, the rise of the East, the challenges of China, and our own ageing population.

Some of the changes required should appeal to the free marketeers. We do need to reform our planning system to get more and better housing built, get infrastructure into place, and make better economic use of our urban spaces. There are some business taxes that can be cut – encouraging investment in technology and research and development, for example – and regulations and legal frameworks – on the use of data, life sciences and public procurement, to name just three – where we can exploit the freedom gained after Brexit.

But these are specific changes, to be made within a mixed approach that uses a stronger, more strategic state to rebalance the economy – attracting private investment, funding infrastructure projects, stimulating nascent industries and backing those in which we already excel, providing more technical education and retraining for those who need it.

With the Tories in the doldrums, MPs grumpy about tax rises and a sense of drift in government rather than vision and drive, many Conservatives are starting to look towards simple and comforting ideological templates to rediscover a sense of energy. That is understandable, but it is also a mistake.

The challenges we face and the problems we need to put right require more. Yes, some targeted tax cuts and changes in regulation where they make sense. But investment, active government, and decision-making for the long-term, too. Such an agenda – coming from a patriotic and positive Conservative government, robust on the culture wars at home and standing up for Britain abroad – would be radical, and yes, still fresh and exciting.

We just need a government willing to choose its path, make its case – and tell some of its more ideological supporters that we can still build a new Jerusalem, it just looks nothing like a new Singapore.