Pressure mounts on Jeremy Corbyn over position on single market, poll suggests

But the poll also highlighted the strength of opposition within Tory ranks to Theresa May’s status quo preference for the two-year transition period.

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It found that 74 per cent of Conservative MPs believed it would be unacceptable for freedom of movement to continue during this 2019-2021 period while 63 per cent opposed the European Court of Justice having jurisdiction in the UK after Brexit Day; views that go counter to those of the Prime Minister, who has said her Government would be prepared to accept current EU rules during the transition period.

Professor Anand Menon, Director of The UK in a Changing Europe, said: “Brexit presents a stark challenge to the leaderships of both major political parties.

“Their views are at odds with those of their own MPs. This promises to cause significant problems for both Theresa May and Jeremy Corbyn. The Prime Minister, in particular, might face considerable opposition from her own backbenchers when it comes to securing the kind of transitional deal she has indicated she wants.”

The MPs’ poll follows a survey for The Observer, which found 56 per cent of Labour voters wanted the party to back permanently staying in the single market and customs union.

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Last week, 48 Labour MPs defied Mr Corbyn to support an SNP amendment to the EU Withdrawal Bill for the UK to stay in the European trading zone.

The policy divide within Labour was further illustrated by comments from Richard Leonard, the Scottish Labour leader, and his colleague Ian Murray, the former Shadow Scottish Secretary.

Official Labour policy is for Britain to leave membership of the single market and customs union after the two-year transition period but then have a “variant” of single market membership and be a member of “a customs union” with the EU.

But appearing on the BBC’s Sunday Politics Scotland, Mr Leonard spoke in favour of Britain staying in the current customs union, saying there was a “compelling case” for it.

“That would certainly provide us with a tariff-free trading area to be a part of; so that has an appeal to it,” he declared.

When it was put to him that this was not the view of Mr Corbyn, the MSP said: “Well, yes. There are issues around the timing of positions being taken. There was a proposition put to Parliament, which was too premature, which was why not just Jeremy Corbyn but Keir Starmer and the whole of the PLP took a decision not to vote for that amendment.”

Asked about Britain staying in the single market, Mr Leonard said this would be problematic as there would be a membership fee to pay but with no power to make the rules; as is the case with Norway. “I don’t think it’s necessarily an advantageous position,” he added.

Earlier, John McDonnell, the Shadow Chancellor, told BBC 1’s Andrew Marr Show, that Labour in power would negotiate with Brussels so that the UK would enjoy the benefits of the single market.

“On the four freedoms - immigration rules were an issue in the referendum campaign - there is a way we can negotiate around that, which would be acceptable to our European partners. It would be reform of the single market. It would not be the same single market but would be access to a single market.”

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But Mr Murray, who represents Edinburgh South, tweeted: “What utter disingenuous claptrap. The EU has made it clear that you can’t be in the single market with ‘all the same benefits’ without participating in ‘the’ single market. If you want all the same benefits, you have to be in it.”

The SNP leapt on Labour’s differences, claiming there was a gulf between Mr Corbyn and his party on EU withdrawal as “wide as the Clyde” and called on the party leader to ditch support for the Conservatives’ hard Brexit.