In the debate about the government’s Brexit strategy, a good deal of ink has been spilt on the finer distinctions of the single market and the customs union.

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Tuesday’s speech by the prime minister – which confirmed she plans to take Britain out of the single market and parts of the customs union – will doubtless lead to more. But I’m not sure how much clarity this debate has provided – or will provide.

In my Bloomberg speech last December, I attempted to put Labour’s position succinctly by focusing on function not form.

I indicated then that Labour would push for a Brexit model that maintains and protects our ability to successfully trade goods with and deliver services to the EU.

I spelt out what that meant: a model that ensures continued tariff-free trade for UK businesses with the EU; a model that ensures any new regulatory frameworks do not add bureaucratic burdens or risk harmful divergence from the EU market; a model that protects the competitiveness of our services and manufacturing sectors; and a model that ensures that existing protections at work provided by the EU are maintained.

Having travelled across the country in the last three months, it is clear to me that businesses, both large and small, as well as many trade unions and working people, agree with this approach.

On Tuesday, Theresa May accepted the importance of these demands and promised to aim for “tariff-free trade with Europe” and a “comprehensive” free trade agreement that would ensure the “freedom to provide financial services across national borders”. She also stated that she wanted to “protect the rights of workers” set out in European legislation.’

That was the right thing to do. It is also important that the prime minister finally accepted Labour’s demand for there to be a vote on the final Brexit deal. This will ensure there is proper grip in the process and a key role for parliament in holding the government to account.

But there were also significant gaps in the prime minister’s speech – in particular over how she plans to deliver on these objectives.

That will take a lot of explaining, and she is taking a significant risk by giving up on membership of the single market and parts of the customs union. This will alarm many businesses and trade unions, so it is vital the government now produces robust economic analysis and a plan for delivery to support her decision.

The prime minister’s comment that the government does “not seek to hold on to bits of membership as we leave” also leaves serious questions about our future role in a wide range of common EU agencies.

Does this mean, for example, that we will soon be outside of the European Aviation Safety Agency, which certifies aircraft before they are allowed to fly? The European Medicines Agency, which ensures all medicines in the EU market are safe and effective? Or Europol and Eurojust – agencies I worked closely with when I was the director of public prosecutions and I know have been vital in tackling cross-border crime and terrorism? If so, this would be profoundly counterproductive.

This uncertainty is compounded by the prime minister’s threat to “change the basis of Britain’s economic model” if she fails to get the agreement she wants. We have to assume this is not a hollow threat and that the prime minister is willing to rip up many of the economic policies and principles that have guided successive UK governments for decades.

This brings into question her commitment to a whole host of social, economic and workplace rights. There is no mandate for the government to do this and it would – contrary to the prime minister’s belief – be an act of self-harm for Britain, and diminish our place in the world.

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Labour will of course fight against this throughout the negotiating process. We are also actively considering amendments to any legislation the prime minister may be required to introduce after the Supreme Court makes its imminent ruling on the article 50 case.

So while we did not learn everything about the prime minister’s intentions for Brexit, we did learn more. Frankly it is extraordinary it has taken this long, and that the prime minister chose to make this announcement in a speech rather than in parliament.

But there is now the basis of a plan. The prime minister owns it, and the decision to take Britain out of the single market is hers alone.

What matters now is how she delivers the aspirations she has set out. That is how this prime minister and this government will be judged.

Labour will hold her to account every step of the way.