When it comes to whether Britain should remain in the European Union, almost all political parties and traditions – Labour, the Greens, Liberal Democrats, the SNP, Plaid Cymru, and half of the Tory Party – agree that we are better off in Europe.

But that doesn’t mean we all have the same reasons for wanting to stay in. A few days ago Jeremy Corbyn set out the Labour case. When it comes to jobs, investment, growth, security and our influence in the world we are clearly stronger in Europe. But we are also making a Labour argument about workers’ rights that really matter, to millions of working people and the trade unions that represent them.

Labour has changed its view on Europe since 1975, in part because the world has changed but also because of the benefits that Europe has brought to people at work. At a time when the Tories were undermining workers’ rights back home, Jacques Delors, in his celebrated speech to the Trades Union Congress in 1988, opened our eyes to Europe’s potential to strengthen them. And as more and more workers across Europe discovered that their firm now had an owner from another EU country, cooperating with colleagues across the Channel became the norm.

Which rights should my constituents not be entitled to any more when they are at work?

And Europe was as good as its word. It helped to guarantee paid holidays, improved maternity and paternity leave, put limits on working time and gave better protection to agency and temporary workers. By ensuring these rights across borders, it helped stop a race to bottom that globalisation, left unchecked, could otherwise bring.

That’s why Frances O’Grady, the general secretary of the Trades Union Congress, is backing remain. It’s why unions including Unite, the GMB, Unison and Usdaw are all backing remain. And Labour is backing remain to protect these rights.

Millions of people in the UK are guaranteed a minimum of four weeks’ paid holiday. Workers are guaranteed 11 consecutive hours’ rest in any 24-hour period, a 20-minute rest break if the working day is longer than six hours, a minimum of one day off each week, a working week limited to on average 48 hours a week, and limits to night work of an average eight hours in any 24-hour period.

More than 8 million part-time workers in the UK have the same rights as full-time workers. About three-quarters of these are women. It was a European court of justice ruling that helped part-time workers to have the same rights to join occupational pension schemes as their full-time colleagues.

About 13 million women in work are protected from discrimination as a result of equality legislation; 340,000 women receive paid maternity leave each year in the UK. In addition, 1.6 million people on temporary contracts now have the same rights as permanent workers. That’s an awful lot of people protected, and yet the Brexiters scoff at those rights.

The employment minister, Priti Patel, a prominent Tory Brexiter, has called them a burden and would like to halve them. Boris Johnson said it was “very disappointing” that Britain had not made “changes to employment law”, complaining that we “need to weigh in on all that stuff, all that social chapter stuff”.

Cameron’s former adviser Steve Hilton has complained that “membership of the EU brings with it constraints on everything from employment law to family policy”. And when Chris Grayling was asked what European “red tape” he disliked, he referred to health and safety laws.

Their target is very clear, but the specifics of what they want to do, and which of our rights they want to get rid of, are not yet clear.

Our own bad habits have brought Britain to the brink of Brexit | Martin Kettle Read more

So my challenge to them is this: it’s time for you to come clean: which rights that the EU today guarantees for British workers do you want to get rid of if we leave? Which rights should my constituents not be entitled to any more when they are at work? Is it health and safety, limits on working time, or rights for part-timers?

And why should we trust a Conservative government in Westminster to protect them if we leave, when so many Tory Brexiters clearly have so little enthusiasm for them?

Of course, the reason why the Brexiters won’t go into any more detail about their plans is because they know British workers would be appalled. And the vast majority of businesses don’t want these rights to be eroded either.

I spent 20 years working for the trade union movement before becoming a Labour MP. I’m proud to have done both jobs. The union movement has achieved a huge amount in the past century or so. It has secured important rights at work, tackled unfair discrimination and ensured that Britain is one of the safest places in the world in which to go to work.

And because we know how hard it was to win those rights, the whole Labour movement is united not only in pride at their achievement but in determination to protect them. And that’s why, Labour, the trade unions and millions of British workers will come together on 23 June and vote to remain in the EU.