Shadow chancellor says no need for split on Brexit as party may still back people’s vote

John McDonnell has warned Labour MPs on the verge of quitting they could cause a decade of Thatcherite Tory rule, adding there was no need for a split over Brexit because the party may still back a second referendum.

The shadow chancellor said MPs thinking of leaving could be responsible for losing seats to the Conservatives, as happened in the 1980s when four senior party figures quit to form the Social Democratic party (SDP).

“It would be like the 1980s. In my constituency in Hayes and Harlington we had a Labour MP join the SDP and we lost the seat to the Conservatives,” he told the BBC’s Andrew Marr Show. “And it basically installed Mrs Thatcher in power for that decade. I don’t think any of the people who have even been mentioned around this split would want that.”

Labour figures including Chuka Umunna, Chris Leslie, Luciana Berger, Gavin Shuker and Angela Smith have been rumoured for weeks to be on the brink of leaving the party over Brexit and concerns about how antisemitism complaints are being dealt with.

Michael Dugher, a former MP, aide to Gordon Brown and senior figure in Ed Miliband’s shadow team, quit Labour this weekend claiming the party he joined nearly three decades ago “no longer exists” and argued it was “institutionally antisemitic”.

However, McDonnell said on Sunday there was no need for a split as the party was holding together on all of the key issues.

“On all the issues people have raised as a reason for a split, we’re dealing with [them]. For example on Brexit we’re holding the party together. Those saying we’ll split over a people’s vote, well, we’ve still kept that option on the table and it might come about. Why split over that? It’s ridiculous,” he said.

He said the party may still come to the conclusion a second referendum is necessary, especially if parliament does not back Theresa May’s deal.

“You’d only go back to the people in extremis, if you can’t get a deal agreed through parliament or if a deal isn’t going to protect jobs and the economy, you’d have to go back to the people, I think that’s right,” he said.

He also said Labour would look at a proposal put forward by the backbenchers Peter Kyle and Phil Wilson to back a sort of “confirmation referendum” if parliament does agree a Brexit deal.

He acknowledged the party had not dealt with complaints about antisemitism fast enough but the system was being reformed.

McDonnell also rejected the claim he had effectively asked for a loyalty pledge from Berger, who was subject to antisemitic abuse while heavily pregnant and was rumoured to be one of those planning to leave the party.

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But he said he had no problem with the loyalty pledges circulating online, with some members urging MPs declare their allegiance to whoever is elected as leader and their preference for a Labour government above all others. Senior figures such as Dawn Butler and Ian Lavery, the party chair, have put their names to it, but other MPs have resisted, with Anna Turley and Lucy Powell saying their Labour membership cards were enough of a loyalty pledge to the party.

McDonnell, who has signed the pledge himself, said: “People wanted reassurance from all of us that we are Labour through and through.”

The shadow chancellor’s words on Brexit did not appear to placate Leslie, who said McDonnell was “clearly rowing back on Labour’s conference policy” by saying a second referendum would be looked at only in extremis.

“There’s a disastrous Brexit in less than 1,000 hours. And UK Labour stands on the sidelines pretending to face all ways. What an utter tragedy,” he said.

Smith added: “Theresa May [is] not the only one ticking the clock down.”

However, other Labour MPs were buoyed by McDonnell’s claim that he would look at the plan put forward by Kyle and Wilson. They hold out hope that the leadership will be persuaded of the need for another referendum if Labour’s proposals fail to win over parliament.

Kate Green, a Labour MP who supports the People’s Vote campaign, said: “It is welcome that John McDonnell has today confirmed that Labour’s proposals need to be brought forward by the end of this month and that if they can’t be agreed in parliament then the party will have no alternative but to follow its conference policy and start campaigning for a people’s vote.

“It’s also encouraging that he also confirmed that the party leadership is willing to look at new compromise proposals to avoid the threat of a no-deal Brexit by approving a deal – but only subject to it being put to the public.”