Billy Bragg has said Boris Johnson was “relatively harmless” when he famously brought the politician to Glastonbury in 2000 but warned “you have to be careful who you elevate to positions of celebrity”.

The folk singer, who has organised the festival’s Left Field tent, said he has not been in contact with the Prime Minister since giving him a documented tour of Glastonbury 22 years ago.

Speaking to the Glastonbury Free Press, Bragg said: “I tell people it was just a bad trip and I don’t know how it ended up on YouTube.

“I thought it was just some bad magic mushrooms but actually it must have really happened. In my defence, he was relatively harmless at the time.

“It just goes to show you have to be careful who you elevate to positions of celebrity. Then, he was that guy off Have I Got News For You.

“Everybody was really pleased to see him. I can’t imagine if I walked around with him now he’d have the same reaction.”

In the video, singer-songwriter Bragg welcomes Mr Johnson, who is wearing a cream suit with a blue shirt, to Castle Cary train station after he had missed his stop on the train – putting it down to “being in a trance”.

While driving the politician to Glastonbury, the pair discuss the correct way to say Glastonbury before asking punters on their arrival.

In the video, Mr Johnson is introduced to naked activists, and is heard to say: “I fully support your right to be naked.”

He also visits the famous stone circle and delves into an economic discussion, branding the festival a “capitalist extravaganza”.

Bragg told the Glastonbury Free Press: “I think he’s someone who has lived all his life without taking any responsibility for anything: professionally, personally or politically.

“Boris is someone who acts with impunity and to have someone like that running the country is downright dangerous.”

In 2016, Bragg affirmed his support for then-Labour Party leader Jeremy Corbyn as he manned the phones at a campaigning event in London and defended the politician when he was facing a barrage of negative attacks.

Glastonbury Festival 2017 – Day 2
Labour leader Jeremy Corbyn speaks to the crowd from the Pyramid Stage at Glastonbury Festival in 2017 (Yui Mok/PA)

A year later, Mr Corbyn appeared on the Pyramid Stage at Glastonbury and was cheered as he gave an impassioned speech to thousands of people.

Chants of “Oh, Jeremy Corbyn” to the tune of The White Stripes’ Seven Nation Army were part of the rapturous reception he received, as he sought to build on the momentum generated by his party’s gains at the general election.

When asked whether current Labour leader Sir Keir Starmer would muster the same response, Bragg said: “I don’t know if Keir is a festival kind of person.

“To some people it’s absolutely anathema, the idea of wading around in a muddy field on a rainy June afternoon.”

The singer added that he thinks pop music still has the power to bring people together in a political sense.

He said: “Pop is no longer as absolutely central to the youth experience as it was when I started out, but I still think it is capable of bringing people together, politically recharging their activism and helping banish cynicism.

“Taylor Swift standing up against Donald Trump in the election year, for example.”

Bragg will play from 9pm at Left Field following a solidarity for Ukraine debate in the day.