Of all the failings of Theresa May’s election campaign, perhaps the most dismal was the absence of an optimistic vision of a post-Brexit economy. It was as if all the mood music of George Osborne’s “Project Fear” had been grafted from the Remain campaign to the 2017 general election. Mrs May’s campaign was built on the language of defence (“strong and stable”). At no stage did she argue the benefits of global free trade. At no stage did she use the language of prosperity. And at no stage did she talk about what a successful 21st-century economy needs to look like – global, networked, knowledge-based, free to innovate. And it is no wonder that Britain’s choice to leave the EU is playing so badly abroad. Instead of setting out a new global example of free trade, Mrs May is circling the wagons, rejoicing in “no deal is better than a bad deal”. Not once has she ventured on to the continent to set out a confident, optimistic vision of our future relations with Europe, of our historic ties and commitment to trade and co-operation.It is close to midnight for the Conservative government. To have any hope of reversing the surge of support for Jeremy Corbyn’s suicide economics, it needs to relentlessly set out the case for a thriving economy. The message must be crafted for the young, for it is they who will inherit this economy and it is they who are being taken in by Mr Corbyn’s blandishments. A core component must be a more generous vision of immigration, which recognises the limits to the absorption capacity of some communities but equally recognises the vital importance of skilled workers and the place of our universities at the heart of any knowledge economy. Students must be taken out of the immigration numbers. And our universities must be brought together to help set a national strategy for the knowledge economy. And above all, the government needs to set out the case for free trade. At the recent Prosperity UK conference, set up to discuss Britain’s future after Brexit, Sir Lockwood Smith, former New Zealand trade minister, spoke about his country’s journey from protection to free trade. In the 1980s, New Zealand was close to a basket case, locked into a Corbyn-style model of nationalised industries, state subsidies and protection. They had food mountains and wine lakes. In 1984, the government launched a 180-degree turn. It embraced unilateral free trade. The result has been a 30-year boom and New Zealand is now one of the most prosperous economies in the world.In 1985, for example, New Zealand erased subsidies on lamb, which had been as high as 90 per cent. Since then the productivity of the country’s lamb industry has risen 107 per cent. In 2008, it became the first economy to agree a bilateral trade deal with China. The benefits of that deal in terms of trade between the two countries have exceeded the estimates of the New Zealand Treasury 11-fold. The UK needs some New Zealand spirit. We need trade deals with the EU, India, the US, Australasia and China. We need to capture the opportunities in emerging markets. The EU does not have trade deals with any major economies except South Korea and Canada. In the 1840s, Richard Cobden and John Bright showed how lower corn tariffs would improve the standard of living of the poorest in society, let alone the “just about managing”. We need the same campaigning spirit and moral leadership today. The repeal of the Corn Laws in 1846 heralded the greatest period of prosperity in British history. An “open” Brexit can unleash a new era of opportunity and wealth creation, and improve living standards for all. It is time the government started to tell this story.