There is a weary inevitability about newspaper reports that Theresa May will confirm in her much-anticipated speech on Tuesday that Britain is heading towards a hard Brexit outside the European single market and customs union. Last October, the Prime Minister signalled that regaining control of the UK’s borders and ending the jurisdiction of the European Court of Justice would be her top priorities in the Brexit negotiations.

Although there has been intense activity since then inside a government that started with a hopelessly blank page, it seems little has changed, and that May remains intent on making immigration her number one red line.

True, the EU has made clear the UK cannot, as Boris Johnson wants, have its cake and eat it: the EU’s “four freedoms” – on goods, capital, services and people —are “indivisible”. But, like the UK, European leaders are inevitably striking hard negotiating poses at the start of a long game. May would be wrong to give up on the single market and customs union at this stage; far better to explore the possibilities of a new EU relationship while remaining in both.

She might be pleasantly surprised: beneath the bluster, opinions are changing on migration. Sensible politicians in several European countries, under pressure from right-wing populists, recognise that free movement can no longer be a tablet of stone. An EU-wide provision allowing member states to apply an emergency brake on migration might just get on the agenda.

Joining the European Free Trade Association, which includes Norway, Switzerland, Iceland and Liechtenstein, should also be considered by May. It would allow continued single market membership – the best way to maximise trade, investment, jobs and growth and cushion the Brexit blow. May’s “bespoke EU deal” should also eliminate non-tariff barriers and give the UK some say over single market rules on labour, health and safety and consumer and environmental protection.

Despite claims by hard-line Brexiteers, May does not have a mandate to leave the single market. Indeed, the 2015 Conservative election manifesto promised to remain in it. She should stand up the Europhobes pushing her towards a “clean break”, who are happy to rely on the tariff-based regime of the World Trade Organisation.

There is no need for the UK to cut off its nose to spite its face. As the Chancellor Philip Hammond has noted, people did not vote to leave the EU to become poorer or less secure. It is true that many voted to curb immigration, but not at any price: a YouGov poll for the Open Britain group found that a majority of Leave voters (54 per cent) are not prepared to be a penny worse off for the UK to regain control of immigration.

As she prepares for difficult negotiations with the EU, May must not have a blinkered focus on migration. The danger is that British intransigence on this issue leads to a bitter divorce, no trade deal and the UK undercutting its natural trading partners by aggressively lowering business taxes in a damaging race to the bottom. Hammond seemed to threaten that course in an interview with Germany’s Welt am Sonntag newspaper, a message that undermines May’s attempt to reach out to the EU 27 in her speech by saying she wants the EU to succeed and prosper.