Before the referendum, the TUC took advice from the noted employment barrister Michael Ford QC about the likely impact of Brexit on workers’ rights. He highlighted a series of risks, from outright deregulation to the more insidious loss of access to the European Court of Justice (ECJ). We used his research to press the case – especially among trade union members, but among working people more generally – for a remain vote.

We accept the decision of the electorate to leave the European Union. But our polling after the vote convinced us that almost no one had voted for weaker rights at work (or the loss of highly paid jobs involved in frictionless, barrier-free trade in goods and services with the rest of Europe). People want to retain the rights that EU directives guarantee: health and safety at work, equality legislation, rights for agency workers and part-timers. And they especially want to keep the right to paid holidays.

Our experience suggests, however, that working people didn’t always feel they had access to those rights. Reduced trade union coverage in the workplace and the high cost of access to justice in Employment Tribunals – only reversed by Unison’s action in the Supreme Court last week – have taken their toll. And they expected that, whatever the government, the rights won through the European Union would be retained. We weren’t so sure, so we pressed the government for assurances.

The prime minister and the secretary of state for exiting the EU have, on several occasions, made promises on these issues. The White Paper that followed the prime minister’s Lancaster House speech in January contained a specific section on protecting workers’ rights. They have promised to maintain and enhance workers’ rights after Brexit.

But they have set out no arrangements for guaranteeing those rights in the long-term. And their insistence on evading the ECJ is troubling. The ECJ has been responsible not only for enforcing the rights conferred by European directives. It has also ensured compliance with the spirit of those directives.

The most egregious example refers to maternity rights. UK courts ruled that a pregnant woman could be dismissed on the same basis as a sick man. The ECJ rightly found that pregnancy was not an illness, and that dismissal on grounds of pregnancy was a clear case of sex discrimination since it was automatically only applicable to women. That’s the sort of interference that Brexiteers want to escape by removing the ECJ from British law.

So how could the government fulfil its promise to maintain and enhance all the rights that trade unions have so painstakingly secured over 40 years of UK membership of the European Union?

The best way to secure those rights, and benefit from any future EU workplace rights, would be to retain our membership of the EU single market (which would also deliver the frictionless, barrier-free trade in goods and serves we seek). Compliance with EU social directives and ECJ decisions is a requirement of single market membership. Both have – in our view, unwisely at this early stage of the negotiations – been described by the government as red lines.

But the alternatives to single market membership do not inspire confidence.

The once-great repeal bill – now the more quotidian EU (Withdrawal) Bill – offers only the prospect of writing EU workplace rights into UK law, but with the Supreme Court replacing the ECJ, powers for ministers over the transposition process that could see our rights watered down, and no protection once we have left the European Union for any of our rights. Theresa May only promised to protect workplace rights while she was prime minister. Hardly a long-term guarantee.

We are pressing for constraints on the Supreme Court’s powers to tinker with workers’ rights; restrictions on ministerial prerogatives so that any change to employment rights would need primary legislation; and a non-regression clause on workplace rights. But even if we achieved these changes to the bill, they would provide no lasting protection.

We are also making the case for any future trade agreement between the EU and UK to preserve and extend our rights. Thanks to the solidarity shown to us by the European Trade Union Confederation and our sister unions around Europe, we have been able to press that case not just with the UK government but with other European governments and institutions.

The experience of labour clauses in other bilateral trade agreements is not good. Often there is just a vague commitment to abide by the core conventions of the International Labour Organisation. And there is rarely anything by way of enforcement. We want specific commitments to a level playing field between the UK and the EU’s social legislation, and enforcement with material consequences through independent arbitration. The EU’s negotiating guidelines for Michel Barnier, its Brexit negotiator, and the European Parliament call for continued adherence to EU social provisions, suggesting that our arguments are being heard.

But there is a long way to go before we can be certain that the deregulatory ideologues of the right and extreme business representatives will be held off. We know they already have plans for slicing away our rights either little by little or – in their dreams and our nightmares – wholesale.

We don’t make a fetish out of single market membership. What’s important to working people isn’t the form of the future relationship between the UK and the EU, but the outcome. They want to protect their rights and their livelihoods, and the best way to do that is to remain in the single market, at the very least during any transition to a new relationship.

By Owen Tudor is Head of European Union and International Relations at the TUC