Krumpet the clown wearing the prison jumpsuit he found in a squat he lived in. Business Insider The rise of Momentum, the organisation set up to mobilise grassroots campaigners to support Labour leader Jeremy Corbyn is one of the most important things to have happened in British politics this year.

The organisation has come from nowhere to propel Corbyn to victory in the Labour leadership election and is still growing as left-wing activists flock to its brand of left-wing activism.

Business Insider went along to the Momentum Arts Xmas Fundraiser on Friday, the first event hosted by Momentum’s arts wing, to find out what is drawing people to the organisation.

Hosted above a pub in Brixton South London, the fundraiser was billed as an event where lovers of the arts could unite through a shared passion for contemporary progressive and socially democratic politics.

The event kicked off with a performance by Opera composer Keith Burstein and two classical singers. Burstein famously tried to sue the Evening Standard newspaper after their music critic slammed his Opera Manifest Destiny for portraying would-be Palestinian suicide bombers as “heroic."

Burstein and his singers performed three songs, the first was a poem by Lemn Sissay was about being “totally stoned on war,” the second was a poem by Ben that began with “everyone loves a spring cleaning, let’s have a humanity cleaning,” and the third was a self-penned operatic anthem called “Rise Up.”

It was very unusual to hear opera being performed in a dark room above a pub as people loudly chatted to each other at the bar and rolled cigarettes in the corner.

Meeting Krumpet the Clown

Jeremy Corbyn, the leader of the Labour party. Reuters By this point in the night, not many people had turned up, but those who had fell into two categories — older, presumably retired people, many of whom were wearing Jeremy Corbyn t-shirts; and young people in their early 20s.

After the opera performance there was a talk from music promoter Lorraine Solomons about the importance of supporting independent musicians, then a performance by a Jazz quintet The Marzec Group.

Their music wasn't political in any way, but halfway through the singer stopped to ask the now growing crowd whether they were “behind Mr Corbyn.” “Yes,” the audience cheered back.

There was a brief break from musical performances while they set up the stage for speeches.

Business Insider took the opportunity to chat with some of the people attending and met Krumpet the clown. Krumpet, who came up with his clown name while he was “on a substance beginning with K,” said that while he has been going along to Momentum events, he doesn’t want join the Labour party yet in case Corbyn gets kicked out.

Britain's opposition Leader of the Labour Party Jeremy Corbyn applauds as Diane Abbott shadow International Development walks on stage at the annual Labour Party Conference in Brighton, southern Britain 28 September, 2015. Reuters " Jeremy Corbyn is my oldest friend in politics"

Next up on the stage was Shadow Secretary of State for International Development and one of Corbyn’s closest political allies, Diane Abbott.

She received a rapturous, rock star-like reception from the crowd. “Jeremy Corbyn is my oldest friend in politics and I'm beyond proud that he’s now leader of the Labour party,” she told them before giving a short speech about what she believes the future holds for Labour.

I believe that under Jeremy Corbyn’s leadership, the Labour Party and the Labour movement is going to go from strength to strength. And I think in Jeremy Corbyn’s leadership, for the first time in my lifetime, there’s a Labour leader that shares all of our values.

Momentum, and Jeremy for that matter, have been demonised in the mainstream media. But do you know what it means when you’re demonised, and I know about that as a black politician. What it means if you’re demonised is that they’re frightened of you… Momentum and [the] Jeremy Corbyn-led Labour party and the forces that we represent have come too far to turn back now.

Abbott left the stage to rapturous applause from what was now a pretty packed room and was followed by several organisers from local Momentum branches. The event started to feel a bit more like a political rally than an arts Christmas party.

Labour has anarchists and socialists under the same roof

Someone called Libby from Brighton & Hove Momentum was very excited about Corbyn being elected Labour’s leader, enthusiastically reassuring the crowd that “it really is happening” and praising Corbyn for unifying the left:

That’s what Jeremy Corbyn’s done, he’s unified the left in a way that I haven’t seen in my lifetime. You’ve got anarchists, you’ve got socialists ... you’ve got everybody loving him. And every day you should love him a bit more. It’s quite incredible isn’t it?

Someone else from Southwark Momentum gave an impassioned speech about her aspirations for the future — aspirations she believes can only be met if Corbyn becomes Prime Minister:

The Tories like to talk about aspiration. I’ve got aspirations. I think everybody in this room has aspirations. My aspirations are that I can live in a society where my 3-year-old son won’t be saddled with debt if he goes to university, that his school won’t be forced into privatisation by being forced to convert to an Academy, and that he will have a chance of a decent job and an NHS that will provide for him as he grows older just like it provides for us.

Diane Abbott was very popular with the crowd Business Insider It was weird to hear her talk about tuition fees and academy schools so negatively. Tuition fees and Academy education were introduced by Labour.

Independent reports have shown that Academies are improving education standards across the country.

In Diane Abbott’s constituency of Hackney, the schools used to be so bad Abbott claimed she was forced to send her son to a £10,000 a year private school so he wouldn’t end up in a gang.

The Mossbourne Community Academy in Hackney is now one of the top performing inner city schools in England. It replaced Hackney Downs School, a place so bad it had been described as “the worst school in Britain.”

Laura from Lambeth Momentum was up next and she regaled the crowd with the story of a man called Sam who attended Lambeth Momentum’s debate about Syria. Apparently Sam was the only person in a room of 65 who thought that bombing Syria was a good idea. Laura was so angry at Sam that she broke into a slam poem:

Sam man, we don’t want to ban you

We just want you to understand

That you are welcome to join us on the righteous side

Just don’t get stuck on the right who can’t abide

That we are turning the tide

After several verses telling Sam that he needed to “get his s*** together,” the poem moved on to praising the “positivity” and “humane common sense” of Momentum:

We are Momentum

We are positive

We are determined

We are how to do what’s right

You can listen to the entire Slam poem below:

Momentum claims that they are proud to create organising space which are "safe for all." So it was odd that they allowed someone to humiliate Sam like that.

The final performance Business Insider stayed for was a dramatic reading by Momentum activist Robert Palk from his upcoming novel Animal Lovers. The book is a comic novel about a man whose wife leaves him to go and protest against the badger cull. After he finished reading Palk told the crowd:

I hope you all in Momentum take the fight to the real enemy, by which I mean slightly less left wing Labour members and MPs.

It wasn’t clear if he was joking.

The left-wing comedian who was billed to finish the night was running late and most of the crowd had migrated to the smoking area on the roof, so Business Insider got an Uber home.