03/04/2017 14:31 BST | Updated 03/04/2017 17:53 BST

Jeremy Corbyn Facing Fresh Resignation From His Top Team As Head Of Events Prepares To Quit

Aide had said leader should be allowed to 'fail in his own time'

Jeremy Corbyn is facing yet another resignation from his top team, HuffPost UK has been told.

Gavin Sibthorpe, the head of events for the Labour leader’s office, has told colleagues he is ready to quit, one party source claimed.

Sibthorpe became infamous among party circles for his remark to a ViceNews documentary in 2016 that “the best way” to remove Corbyn would be to “let him fail in his own time”.

The phrase became jokingly known among MPs as ‘The Sibthorpe Doctrine’, and has been adopted by even Corbyn’s critics since his second landslide leadership election.

Corbyn has already suffered the departure of four other key staff from the Leader’s office in recent weeks.

The party refuses to comment on staff matters, but supporters of the leader said that Sibthorpe had not notified the party of any resignation.

However, it is understood that he met his union rep in recent days after a row over the leader’s visit to Wales. He is currently on leave.

Seen as a leadership loyalist, and well-liked on all sides of the party, Sibthorpe himself was a constant companion and ally of the leader as he criss-crossed the country to persuade voters that his new style of politics could be popular.

He unwittingly turned out to be one of the stars of the ViceNews documentary last year, when the online news organisation had unprecedented access to Corbyn and his team.

At one point, Sibthorpe was asked by the film makers what MPs would o if Corbyn failed to improve the party’s performance.

“If they want to get rid of him, the best thing to do would be wait and...let Jeremy fail on his own - I don’t think he will - but fail on his own, in his own time.”

His advice was not taken up by members of the Shadow Cabinet at the time, who decided instead to try to remove Corbyn weeks later.

Tasked with organising visits, as well as advising on ‘dress sense’, Welsh-born Sibthorpe was also caught on camera showing how upset he was when David Cameron attacked his leader in PMQs over remarks about Palestinian group Hamas.

“I don’t think I’ve ever seen a Prime Minister act in that way...I just get upset about it, you know.”

PA Archive/PA Images
Defeated leadership challenger Owen Smith and Jeremy Corbyn

Within weeks of the ViceNews documentary being aired, Britain voted for Brexit in the EU referendum and Corbyn faced calls from his Shadow Cabinet and MPs to step aside.

But despite a vote of no confidence from nearly 80% of his MPs, and the mass resignation of many of his shadow front bench, he went on to easily beat challenger Owen Smith in a leadership contest.

Since then, many in the Parliamentary Labour Party (PLP) have accepted that another ‘coup’ attempt would be counter-productive and have spent months trying to avoid public criticism of their leader.

With opinion polls continuing to show the party is up to 19 points behind the Tories, and Corbyn’s own ratings at new lows among Labour supporters, the MPs believed their tactics have been vindicated.

Sibthorpe was on the first Corbyn leadership campaign in 2015, when the Islington North MP defied the bookies and pundits to win by a landslide against Andy Burnham, Yvette Cooper and Liz Kendall.

Yet in recent weeks he has told friends how unhappy he is working in the leader’s office.

“Everyone likes Gavin, no matter which bit of the party they’re from. He’s loyal to Labour. It says a lot that he’s quitting,” one party source told HuffPost UK.

Corbyn supporters will be determined to ensure that Sibthorpe does not leave and that any dispute can be resolved.

Allies of the leader denied claims last month that he was facing an “exodus” of staff from his top team, after trade union, press and communities specialists all quit.

Nancy Platts, the trade union liaison manager in the Labour leader’s office, handed in her notice after nearly 18 months in post, to take a post helping charities with PR.

Matt Zarb-Cousin, media spokesperson for Corbyn, and Jayne Fisher, in charge of contacts with community and minority ethnic groups, are also leaving.

The leader’s head of economic policy, Mike Hatchett, resigned to join the Government’s Brexit department.

Former chief of staff and campaigns director Simon Fletcher also quit in February amid concerns about a lack of direction and overall competence in Corbyn’s office.