The grotesque betrayal of the generation that most detests Brexit is like some lost Restoration comedy. The Country Wife at Theatre Royal Haymarket. Photograph: Tristram Kenton for the Guardian

Nothing is more important to the creative industries than innovation. Without it, well quickly lose our international pre-eminence and a sector that in 2014 was worth 84bn, and is growing at twice the rate of the wider economy, will shrivel and die.

New ideas, contrary to romantic myth, dont emerge fully formed from the imagination of a lone genius. By and large, theyre the result of the kind of creative ferment that feeds off direct exposure to whatever and whoever is breaking new ground, wherever it is happening. In the 19th century, when Britain really was the country the Brexit nostalgists want back, you could work anywhere without a passport. Isambard Kingdom Brunel studied in Paris before he came home and revolutionised engineering. John Ruskin developed his thinking on architecture in Italy. George Eliot lived for eight formative months in Germany; three years later she published her first novel.

The young are still ground-breakers, and theyve been the chief beneficiaries of the freedom of movement that has come with EU membership. It cuts both ways: creatives from the rest of Europe come here because they want to be part of a thriving creative economy. They bring new energy to architecture, fashion, design, music, film.

Its no surprise, then, that before the EU referendum, a survey of members of the Creative Industries Federation showed 96% support for remaining in the EU. Arts world groupthink, sneered the Brexit operative who was sent into the TV studios by the leave campaign to urge us to subscribe to alternative groupthink about taking back control. And if groupthink is the consequence of the individual experience of everyone in the group, maybe it was.

Starting out in the theatre, I worked in France, Germany and the Netherlands. More recently, Ive employed artists from all over Europe, and I felt nothing but shame when the National Theatres head of wigs, hair and makeup reminded me recently that he has yet to be assured he can continue to live his life here. Hes Italian, but he has worked and paid taxes in the UK for 15 years.

Young British theatre-makers hit the road and bring back what they discover from living and working in Berlin and Paris

Meanwhile, young British theatre-makers, impatient with the theatre establishment, hit the road and bring back to our theatre what they discover from living and working in Berlin and Paris. Theyre inspired by what can be achieved with European levels of public subsidy, which accounts for as much as 95% of the income of some German theatres. Its not all upside. With lavish subsidy comes political control: government paymasters have recently turfed out admired directors of theatres in Germany, Poland and France. Our own system of arms-length funding via the Arts Council protects artists from political interference. This system is not the European norm, but at no point during the past decades has the EU tried to bring it into line. In the arts, we cant take back control because it was never given away in the first place.

In any event, the freedom to work and learn in the rest of the EU has been every bit as crucial to British creative success as the freedom to hire talented Europeans to work in Britain. During the election campaign, freedom of movement was presented as a one-way street: unrestricted immigration from the EU is the problem; border control is the solution. Continued membership of the single market is off the table, even for the Labour party, which continues to equivocate about a deal that would genuinely protect the interests not just of the economy but of the young people who voted for it in such numbers.

The students who delivered Canterbury for Labour deserve the right that their predecessors enjoyed to work and live without visas outside this country, if only to be able to come back and turn its failing economy around. In our brave new self-controlled world, the not-for-profit arts sector may miss the modest EU subsidies that it could once apply for. The commercial theatre, of which I am now part, may struggle with a doubled immigration skills charge. But far scarier is the prospect of a generation of creative talent crabbed by insularity and stunted by the delusion that our native genius, once unfettered, will be enough to see off the opposition.

The grotesque betrayal of the generation that most detests Brexit is like some lost Restoration comedy. The Restoration playwrights, their eyes wide open to the worlds lust and avarice, show young people with names such as Heartfree, Constant and Worthy doing battle for the future with their self-regarding seniors. Imagine a creaky burlesque called Lady Woodens Stratagem. Like so many old comedies, its not funny. Lady Wooden thinks herself extremely clever but turns out to be dense, and is held hostage by characters whose names announce their hypocrisy and malevolence: Backstab, Brute, Bullingdon, Gove. They scheme to cheat the young of their inheritance. The play ends badly, but theres no reason why it cant be rewritten.

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Freedom of movement helped British creativity thrive. Its loss will diminish us - The Guardian