The EU referendum was a vote on immigration: this, at least, is the clear presumption of post-Brexit politics. Rather than merely tinkering with the rules around free movement, Theresa May is taking the opportunity presented by Brexit to launch a full-scale Tory revolution. But make no mistake, May’s speech was a pitch to a perceived so-called “nativism” that the Tories believe in. Meanwhile, Labour currently appears in denial about the need for a debate around free movement, and certainly there is no clear policy to speak of.

Free movement will clearly be key in any post-Brexit settlement. The Tories have now laid out their stall on immigration. May has made her position clear that it will be acceptable to sacrifice our membership of, or full access to, the single market on the altar of restrictions on immigration. Indeed, she has tacitly indicated that this is the outcome she is expecting from the negotiations.

There are plenty of holes in May’s new policy. How will she cope with limited or no access to the single market? Will Britons lose their freedom of movement? What will happen to the millions of British citizens working or retired in EU countries? Is it ethical to require firms to list their foreign workers? Will the NHS collapse if fewer foreign doctors and nurses and other staff are allowed to work in the system?

And yet Labour have summarily failed to hold May and her government to account on their pronouncements on freedom of movement and immigration more generally.

To be fair, various Labour politicians have spoken since the referendum about free movement. But the views and policies they appear to outline vary wildly depending on who you are listening to.

Jeremy Corbyn’s position appears to be a firm opposition to any restrictions on immigration, and he has (rightly, in my view) condemned the anti-immigrant rhetoric we have heard from the Tories as “xenophobic”. Elsewhere, prominent younger MPs such as Rachel Reeves and Chuka Umunna have proposed ending free movement altogether.

In a Fabian Society publication, Reeves said: “Ending free movement has to be a red line post-Brexit. Subject to that, we need the greatest possible access to the single market.”

Umunna echoed this as more recently he said that whilst ideally the post-Brexit deal would include membership of the single market, he was clear that free movement of people would have to be axed even if that meany sacrificing our membership of the trading group.

“If continuation of the free movement we have is the price of single market membership then clearly we couldn’t remain in the single market, but we are not at that point yet,” he said. He subsequently clarified: “The government should aim for both in its EU negotiations” – to end free movement while retaining membership of the single market.

Corbyn has also said he is relaxed about Britain leaving the single market but has not signalled whether he would accept an end to freedom of movement. For some Labour MPs, especially on the left of the party, any restriction whatsoever on immigration is prima facie unacceptable.

This discordant polyphony of Labour voices is arguably the price we pay for a leader loved by the selectorate but estranged from the majority of the PLP. There has seemingly been little to no debate either at Labour Party conference or across CLPs with respect to freedom of movement and yet this is the issue that will likely be at the heart of the Brexit negotiations.

In order to be able to play its part in this turning point for our nation, and to perform the role of an effective Opposition, Labour desperately needs a formal and consistent policy on free movement. In the absence of this, the best we can hope for is a series of ad hoc commentaries by Labour MPs with varying, sometimes conflicting, views on the issue. The issue of free movement is fraught with difficulty and the position we adopt will go on to define this country for the next generation. Labour’s vacuum risks being filled by UKIP, especially in the northern heartlands. Labour simply cannot afford to flounder on freedom of movement.