A mood of defiance was in the air as hundreds of Jeremy Corbyn supporters turned out to an emergency London rally to show their support for the Labour leader last night (29 June). The event, organised by pressure group Momentum and held outside the School of Oriental and African Studies (SOAS), came amid a revolt from Labour MPs over Corbyn's leadership.

The parliamentary party had overwhelmingly backed a motion of "no confidence" on Tuesday (28 June) after mass resignations from Corbyn's shadow cabinet in protest over the left-winger's alleged lacklustre EU referendum campaigning for Remain, and his decision to sack Hilary Benn as shadow foreign secretary.

But Corbyn, who attracted almost 60% of the vote in the 2015 Labour leadership election, has vowed to stay on. Momentum, his Praetorian Guard of activists, has organised a number of rallies in reaction to the leadership challenge. Their previous demonstration was held in Parliament Square on Monday to coincide with Labour's weekly parliamentary party meeting.

Shadow chancellor John McDonnell, a close ally of Corbyn, last night branded the get-together as "like a lynch-mob without a rope". He said: "On Monday night we had the parliamentary Labour party, which was not a meeting to enjoy. In fact, it was like a lynch-mob without the rope.

"MP after MP were getting up, urging Jeremy Corbyn to resign on the basis that we could not win elections with him. The irony of it was – the first item on that agenda of that meeting was welcoming the victor of the Tooting by-election [Rosena Allin-Khan]."

Matt Wrack, the general secretary of the Fire Brigades Union, and the new shadow health secretary Diane Abbot, another close ally of Corbyn's, also addressed the rally before the Labour leader spoke. Corbyn issued a call of unity: "Surely together we have strength, surely together we can harness the technology we have got, and together we can be very strong and not be afraid of press barons who attack us. Not be afraid of those who only offer us inequality in society.

"It's mobilising people, it's mobilising free-thinking and mobilising ideas in order to concentrate those policies which can improve the lives of everybody in our society. That is why we contested the leadership of this party a year ago and that's why I'm very proud to be carrying on with that work."

But it was not all smooth going for Corbyn during the rally, as he was heckled over the EU referendum result. Zack Polanski, a Liberal Democrat, shouted: "What about Europe Jeremy? Where were you when we needed you?"

The rally was the day before former shadow business secretary Angela Eagle is expected to announce a leadership bid. Labour-affiliated trade unions, including Unite, Unison and GMB, last night issued a joint-statement on the party's turmoil.

"Jeremy Corbyn is the democratically-elected Leader of our Party who secured such a resounding mandate less than ten months ago under an electoral procedure fully supported by Labour MPs," the leaders said.

"His position cannot and should not be challenged except through the proper democratic procedures provided for in the Party's constitution. We urge all Labour MPs to abide by those procedures, and to respect the authority of the Party's Leader.

"While we have stated that we believe a Leadership election would be an unwelcome distraction at this time of crisis, if one nevertheless occurs through the proper procedures we would expect all parts of the Party to honour the result and pull together in the interests of the country, and working people in particular. The only party that can win for working people is a strong and united Labour Party."