Let's concentrate on the positives of EU membership - not the Tory family row

A casual viewer tuning into last night's EU debate on ITV might have wondered if they were still watching the particularly vicious episode of Emmerdale that preceded it. Such was the level of personal attack. The most important decision facing this country in a generation is in grave danger of turning into a Blue on Blue slugfest, as one Conservative cabinet minister accused a potential Conservative leader of being a liar. And while Amber Rudd might be right that Boris Johnson is more interested in getting his former Eton mate David Cameron out of Number 10 than he is in getting Britain out of Europe, I am more worried about the jobs of British workers that are now at risk in this political mud fight.

Politicians from both sides have a responsibility now to step back and think about what will happen to Britain after the referendum. There is a real danger that, far from defining Britain's place in the world, we are left with racial tension, division and a governing party tearing itself apart – and, if we leave, against the backdrop of a plunging pound, investor flight and collapsing stock market. As companies warn of redundancies, no wonder why even some Brexiters are starting to look over the abyss and question if any of this can really be in our country's interests.

The racism of the "Outers" started as a dog whistle but is becoming a foghorn. We have come to expect it from Nigel Farage, with his disgusting suggestion that British women could face sexual assault from migrants, but when senior Conservatives such as Boris Johnson and Michael Gove base virtually their entire Brexit case on how leaving will reduce immigration (it almost certainly won't, by the way), those who remember Enoch Powell know that they are edging close to stoking something very dangerous.

Sure, they are more careful with their language, but when Johnson likens EU membership to being in the backseat of a mini-cab being driven by someone who doesn't speak English, he knows what he is doing: playing on peoples' fears, and that could have dire consequences on the streets of Britain.

Instead, I have fought a positive campaign. Pointing out that as well as immigrants here working in our health service and boosting business – every authoritative study shows EU migration adds to British GDP – there are also 1.9m Brits living on the continent. Some have retired to the sun, others are young people studying (often courtesy of the EU, incidentally) and many more are working there. Far from being fearful, we should be excited that our young people can work as easily in Paris or Rome as in London or Glasgow.

As well as immigrants here working in our health service and boosting business – every authoritative study shows EU migration adds to British GDP

I have also emphasised that membership gives us access to the world's most lucrative market, and in the service sector, we dominate. Rather than withdraw, lets stick around and push to complete the single market to add an estimated £7bn a year to the UK economy.

Amid talk of what EU membership costs – exaggerated by the Brexiters – I emphasise what we gain. As I travel the country, I learn about infrastructure projects or research programmes funded by the EU. And about EU programmes that give cheap loans to startup businesses or help train apprentices (half a million UK apprenticeships, for instance, have been part-funded by the EU).

But even if Britain didn't get all this back, our EU contribution is scarcely 1% of our budget. In return we have access to a market of 500m people, and the EU negotiates advantageous trade deals with the rest of the world.

But we haven't heard much of this, still less the positive things Europe has done to improve our environment or made our streets safer thanks to the European Arrest Warrant.

I want Britain to be outward looking and open, thriving in a global economy. And where globalisation presents challenges, we can keep big international giants in check through the EU.

I want Britain to be outward looking and open, thriving in a global economy. And where globalisation presents challenges, we can keep big international giants in check through the EU.

This decision is too important for the future of young people to leave to those grumpy about the modern world. This is too big, especially if it leads to not one referendum but three or four as we face the break-up of our once United Kingdom.

That is why I make the positive case while the Conservatives enjoy their family row. It is not their families' futures or their jobs at stake. It is the jobs of people across Britain. But as Michael Gove and Boris Johnson tour the country in a German bus claiming to be Karl Marx and Friedrich Engels, they must know what harm they are doing to British businesses.

As the only party united on the need to stay "In", we are now the only pro-business party. Ignore the slug-fest, have confidence that Britain can thrive in an open world.​

Tim Farron is Leader of the Liberal Democrats and MP for Westmorland and Lonsdale