The trio have built a name for themselves with a balance of socially conscious lyrics and satire but have really come to the fore in recent months after taking legal action over a UK government decision to block funding they had been granted by the British Phonographic Industry (BPI).

Often described as controversial, there is no doubt they are unafraid to say what they think - but argue they are simply speaking up for the deprived areas of Northern Ireland, in a language which is "often ignored".

Plus, there is a lot of tongue firmly in cheek here.

Three friends from Belfast, Kneecap are Mo Chara (Liam Óg Ó hAnnaidh), Móglaí Bap (Naoise Ó Cairealláin) and DJ Próvaí (JJ Ó Dochartaigh, a former teacher who still wears a balaclava initially put in place to disguise himself from his students).

One of their most famous tracks, Get Your Brits Out, has been criticised for being anti-British - but the trio say this is the biggest misconception about the band. And clearly, as it blasts out from a tent in the English countryside, it is loved by the Glastonbury crowd.

"This is a thing that people love to spin, like we're some anti-British band," says Mo Chara, speaking to Sky News following their successful set. "We have English family. We have loads of good friends who call themselves British. It's the British government we don't like."

They come from a "serious" area of the world where there has been "drama, a lot of violence", he says.

"I think we're the first generation… because we came after the ceasefire or just before it, around that time - ceasefire babies, as people like to call us - [...] we're able to joke about these things that were once traumatising for people in our community.

"But every side of the community can take a joke and we don't give people enough credit, that people know how to have a laugh."

"I think being offended is subjective," says Móglaí Bap. "We're having a good time, a bit of craic. There's a lot of fun with it and all these jokes, humour, it's all in context, and you can take it out of context and get offended. But I think genuinely, we meet people from all walks of life and they enjoy it."

Read more:
Glastonbury's greatest secret sets of all time
How politics accompanies the music of Glastonbury
Dua Lipa at Glastonbury: A masterclass from a proper pop star

Unsurprisingly, the trio have locked horns with quite a few politicians.

At the minute, they are embroiled in a legal battle with the British government over the blocking of £15,000 in funding from the Music Export Growth Scheme, which aims to help UK music groups market themselves abroad.

It's a "slippery slope" and sets a "bad precedent", says Móglaí Bap, to only give funding to artists that "align with them… that doesn't make any sense".

They are all taxpayers, he adds, and therefore have "every right" to funding that is available to British artists.

A government spokesperson says they are unable to comment due to this being an election period, but the Department for Business and Trade's decision at the time was that Kneecap's Republican views made them ineligible.

While they await the outcome of the legal case, the rappers are busy performing following the release of their second album, Fine Art, earlier this month, and are also looking forward to their big-screen debut.

The band members play themselves in a biopic about their rise to prominence, set in post-Troubles Belfast, also starring Irish actor Michael Fassbender. The film has been shown at festivals including Tribeca in New York, and the band say the reaction has been "crazy".

Which all means it looks like the fanbase will expand even more when the film is released in the summer.

So while some politicians may fail to see the funny side of Kneecap, there are plenty of young people in Belfast, Glastonbury and beyond who clearly enjoy their irreverence.