Labour's Northern Irish sister party urges MPs to defy Corbyn and back single market plan

Exclusive: The SDLP has written to every Labour MP urging them to back a move to keep Britain in the EEA despite Mr Corbyn having refused support

The Labour leader is not backing single market membership after Brexit (EPA)

Labour’s Northern Irish sister party has written to all of Jeremy Corbyn’s MPs, warning them that his current approach to Brexit will not prevent a hard border with the Republic.

In a letter leaked to The Independent, the SDLP beseeched Labour MPs to back a plan to stay aligned with the single market – which Mr Corbyn himself has refused to support.

The SDLP’s Brexit spokesperson Claire Hanna, urged Labour MPs to act for the sake of peace in Northern Ireland and not for “British political convenience”.

It comes amid a deepening row within Labour’s ranks about its approach to Brexit, sparked when dozens of Labour Lords went against Mr Corbyn’s will and voted to pass a proposal to keep the UK in the European Economic Area (EEA).

Conservative MPs have told The Independent they have enough rebels to pass the plan – which would effectively keep Britain in the single market – through the Commons and make it law, as long as Labour also backs it.

Labour’s current position is that it “respects” the 2016 referendum, that Britain’s EU membership must end, that the country should remain outside the single market and leave the customs union to negotiate a new bespoke customs relationship.

But in her letter, Ms Hanna wrote: “Voters in Northern Ireland rejected leaving the EU. It cannot be right for the majority opinion here to essentially go unheard.

“We don’t believe the issue of the Irish border, and the impossibility of avoiding a hard economic frontier without single market access, was sufficiently addressed during or since the campaign.

 The SDLP is urging Labour to use this opportunity to act in all of our interests by remaining in the EEA

Claire Hanna, SDLP Brexit spokesperson

“It is important to note that customs union membership alone will not prevent such a border.”

Underlining the point, she argues that a hard border “can’t be prevented by clever words in a treaty text or by imagined technological innovations”.

Ms Hanna explains that she is writing on behalf of the entire SDLP to urge Labour MPs to back the EEA amendment, when it eventually comes to a vote in the Commons.

She added: “[A hard border] will only be prevented if we retain full access and full alignment with the single market and customs union. No other solution is possible.

“As a sister party of the Labour Party, the SDLP is urging Labour to use this opportunity to act in all of our interests by remaining in the EEA.”

Turning to the threat to the Good Friday Agreement from a hard border, she says the amendment must be backed to protect the “hard won peace in Northern Ireland”.

She wrote: “As a party committed to the principle of consent and campaigning for support for Irish unity, the SDLP understands the importance of the guarantees offered in the Agreement to all sides as a way of building confidence in the process of political change.

“Abrogating those guarantees for the sake of British political convenience is not a good outcome for those seeking to build that consent for change.”

The words will particularly grate on Mr Corbyn, who prides himself on having been a strong advocate of peace ahead of the Good Friday Agreement.

A total of 83 Labour peers defied Mr Corbyn’s will on Tuesday and voted for an amendment to Ms May’s EU Withdrawal Bill that would effectively keep Britain in the EU’s single market.

The amendment will now come to the Commons, with The Independent having been told Conservative rebels have enough MPs to make it law as long as Labour also backs it.

Such a move could well spark a Tory Brexiteer backlash in the form of a vote of no confidence in Ms May, that would likely bring the government down, sparking an election and an opening for Labour to win power.

But in comments that have infuriated some of his MPs, Mr Corbyn’s office failed to back the amendment, claiming the single market was “problematic” for his plans to intervene in British industry if he wins power.

When asked if Mr Corbyn would back the amendment, his spokesman said it was “not what we are proposing”.

The spokesman explained that staying in the EEA could undermine a future Labour government’s ability “to intervene” in UK industries with particular issues around state aid and reversing privatisation.

With the row over Labour’s Brexit position deepening, Mr Corbyn is set to be confronted on the matter if he attends the next meeting of the parliamentary party on Monday.

On Wednesday, five Labour MPs from the North East wrote for The Independent contradicting party line, warning of the impact on living standards of leaving the single market and demanded a new referendum on the eventual Brexit deal.

Ms May’s cabinet is also deeply divided on Brexit, with the issue of what kind of customs relations to adopt set to be discussed again at a meeting of senior ministers on Tuesday.

Foreign secretary Boris Johnson has denied being disloyal, despite calling the option of a “customs partnership”, said to be preferred by Ms May, a “crazy” idea. Business secretary Greg Clark has said thousands of jobs could be put at risk if the UK does not implement the idea.