Owen Smith, the shadow Northern Ireland secretary, has waded into the row about Labour’s Brexit stance, warning the return of border posts in Northern Ireland will be unavoidable without the UK “effectively retaining membership of the single market and the customs union”.

Jeremy Corbyn expressed renewed scepticism about some aspects of the single market on Sunday, and repeated his assertion that it is not possible to remain inside the single market without being a member of the European Union.

Smith said: “I find that slightly puzzling, because it is clearly possible for us to be outside the EU and inside the single market, as is Norway and other countries.”

As he prepared to visit Northern Ireland and the Irish Republic this week to meet politicians and trade unions, marking a year since the power-sharing agreement at Stormont collapsed, Smith said the logical way to prevent the return of a hard border was to sign up to the rules of the single market and customs union.

Asked about Labour’s policy, he said: “The position we’ve got at the moment is very clear, which is that we’ve got to stay in for the transitional period. The position is equally that there has to be a solution to the Northern Irish border, and my view is that can’t be reached without effectively retaining membership of the single market and the customs union.”



He added: “That is an argument that I’m consistently making within the Labour party.”

Smith believes the practical implication of the withdrawal agreement Theresa May struck with the EU27 member states before Christmas is that the UK will end up effectively remaining inside the customs union and the single market.

“It is incredibly important for the peace process that we do not have, cannot countenance, a hard border on the island of Ireland,” he said. ”At the moment the government appears to me to be conceding that the only way in which they deliver on their guarantee of not having that, is that we remain aligned with the rules of the customs union and the single market; or that they come up with some, frankly fantasy, solution.”

Two key paragraphs in the agreement say that if the final UK-EU deal does not obviate the need for border-checks, and a separate solution cannot be found for Northern Ireland, the UK will “maintain full alignment with those rules of the internal market and the customs union, which, now or in the future, support north-south cooperation”.

May was forced to tweak the language to meet objections from the DUP’s Arlene Foster, and the Irish prime minister, Leo Varadkar.

Smith, the MP for Pontypridd, was brought back into the shadow cabinet after the general election in June. In 2016, he unsuccessfully challenged Corbyn for the leadership.

Speaking in advance of his trip to Belfast and Dublin, he urged the new Northern Ireland secretary, Karen Bradley, to intervene to get power-sharing back on track.

“I think we’re at a point of real danger for the Good Friday agreement, and a moment when we’ve got to think very hard about how we keep it alive, as a vehicle for reconciliation in Northern Ireland, and seeing the normalisation of politics in Northern Ireland,” Smith said.

“The thing Karen Bradley has got to realise is she can’t repeat the cycle of failure that we’ve seen over the last year.”

Finally, he called for all Northern Ireland’s parties to abide by the commitment they made in the 1998 Good Friday agreement to share power – or risk the settlement being unpicked.