Jeremy Corbyn allies to demand Tom Watson's scalp if High Court appeal over leadership contest fails

Tom Watson will come under pressure to quit as deputy leader if Labour loses a High Court challenge over its leadership contest.

The Independent understands his position will be viewed as “untenable”if the party loses an appeal against a ruling that overturns a ban on new members voting in the leadership challenge to Jeremy Corbyn.

Many in the party believe the majority of those who have flocked to join Labour’s ranks in recent months intend to use their vote to re-elect Mr Corbyn as leader.

On Thursday Labour officials will appear in court for the second time this week to hear whether their appeal has been successful. John McDonnell, the shadow Chancellor, has already branded the appeal a “deeply disappointing decision by a small clique of people behind closed doors”.

But a senior Labour source told The Independent: “Both Iain McNicol and Tom Watson are on the NEC [National Executive Committee] procedures committee. They sanctioned the freeze date, and they decided to spend members’ money on trying to stop their own members voting. The responsibility for this lies with them. The court case and the appeal will have cost the party £250,000.

“If it doesn’t go the way of McNicol and Watson tomorrow then surely their positions as general secretary and deputy leader of the Labour party are untenable."

Mr Watson, who is known for campaigning on issues including phone hacking and historical child abuse, won the deputy leadership in 2015 after emerging victorious in the third round of voting. Any plot by left-wingers to oust him as deputy leader, however, would follow the same protocol as electing a party leader – it would need the backing of 20 per cent of Labour’s MPs and MEPs, which would likely prove difficult to obtain in the current climate.

Mr Watson’s spokesman declined to comment when approached by The Independent.

The remarks come after the relationship between Mr Corbyn and Mr Watson descended to a new low this week, with the Labour leader’s camp attacking the party’s deputy of “peddling baseless conspiracy theories”. Mr Watson said Labour was being infiltrated by “Trotsky entryists” who had “come back” to bolster Mr Corbyn.

“There are Trots that have come back to the party and they certainly don’t have the best interests of the Labour party at heart,” Mr Watson said. “They see the Labour Party as a vehicle for revolutionary socialism and they’re not interested in winning elections and that’s a problem.”

But the future of Mr McNicol, who has held the position of Labour’s general secretary since 2011, is more uncertain. Just this week Mr Corbyn’s supporters consolidated their grip on party’s governing body after six new members, who are backers of the Labour leadership, were elected to represent constituency Labour parties giving considerable influence to the veteran left-wing leader. They will take their seat on the NEC after Labour’s annual conference in the autumn.

According to the party’s rule book, a general secretary “shall be elected by party conference on the recommendation of the NEC”.

It adds: “S/he shall remain in office so long as her/his work gives satisfaction to the NEC and party conference. Should a vacancy in the office occur, for whatever reason, between party conference, the NEC shall have the full power to fill the vacancy subject to the approval of party conference.”

Shortly after the High Court appeal on Thursday, Mr Corbyn and his challenger in the Labour leadership race, Owen Smith, the former shadow Work and Pensions Secretary, will go head-to-head for the second time in Gateshead.

But speaking on Wednesday, Mr Smith conceded that he faces an uphill battle following the court’s decision to give new Labour supporters the right to vote in the contest. Mr Smith told ITV News: “I don’t know what the split is going to be. I think it’s probably going to be in Jeremy’s favour. It’s very clear that I’m the underdog in this.

“I’d really like to go to some of those Momentum rallies with Jeremy. I’ve asked him to let me attend and speak to the great masses he’s drawing from the Momentum movement. I think that would be really good. It should be an open democratic contest.”