It had been a fun sleepover at Nigel Farage’s house and Jean-Pierre Lihou, a teenager with an appetite, was delighted with his schoolfriend’s mother’s hospitality. “I remember the fantastic cooked English breakfast, as opposed to what you get at a boarding house on a morning,” Lihou recalled. “I was a boarder and he was a day boy,” he said of their education at Dulwich college in south-east London.

Farage was a great mimic, and funny with it, Lihou said. But over time he found there was a darker side to his 14-year-old friend.

“He loved the fact that half of me is from Germany,” said Lihou. “My birthday is one day before Adolf Hitler’s, which at the time you think, you know, ‘ho ho’. But he used to stomp around the playground and chant ‘Oswald Mosley’ [the 1930s leader of the British Union of Fascists]. I didn’t have a clue who that was until about a couple of years later.

“He would go around the school, his boots were the cleanest ever in the world. Used to spend hours with spit and polish and his packet of snuff trying to be the rebel in his army kit, with his camo trousers, just to make a point.”

By sixth form, the two were no longer close. “We were friends until I realised he’s a bit of an idiot,” said Lihou. “Farage used to say things like ‘Hitler was right’ and ‘gas em’, you know, that sort of thing. But he also used to sing this song, which I later discovered was based on George Formby’s Bless Them All.

“He had a whole load of ‘lyrics’ on this which are pretty awful. I can remember it verbatim: ‘Gas em all, gas em all, into the chambers they crawl. We’ll gas all the Paks, and we’ll gas all the Yids, and we’ll gas all the coons and all their fucking kids.’”

Peter Ettedgui said: Farage “would sidle up to me and growl: ‘Hitler was right”.’ Photograph: Tolga Akmen/EPA

On Tuesday, the Guardian reported claims based on the testimony of more than a dozen contemporaries at Dulwich college who claimed having witnessed, or been a victim of, “racist” behaviour by Farage.

One of those who spoke out was the Bafta and Emmy award-winning director Peter Ettedgui.

“He would sidle up to me and growl ‘Hitler was right’ or ‘Gas them’, sometimes adding a long hiss to simulate the sound of the gas showers,” Ettedgui said.

Not every former pupil and teacher who spoke to the Guardian recalled Farage as doing or saying racist things. Farage has responded to such claims of teenage bigotry as “entirely without foundation” and a “smear”.

But Lihou claims to have clear recollections of Ettedgui’s torment. “[Farage] used to say things like, you know, ‘Jude’, to Peter, which is the German for Jew, in the way it was said in the 1930s, a long ‘u’ in a menacing way, you know? It’s pretty awful.

“Peter would become quiet. I think he originally said ‘sod off’, because he’s a fairly robust guy. But he eventually basically went into himself and tried to ignore it. It would subdue him. But he’s a successful film/production/drama guy, and I’ve got school magazines full of Peter doing various productions at a young age, so it wasn’t going to put him off, but it did certainly affect him.”

Lihou said he found Farage’s denials of the allegations strange.

Farage responded to previous claims of racism at school made in 2013 by admitting to saying “ridiculous things … not necessarily racist things … it depends on how you define it”.

When Lihou wrote an anonymous open letter to the Independent in 2019 in which he referred to the chanting of Mosley’s name and the “Gas em all” song’, Farage responded by saying that the “period during which I was at Dulwich was highly politically charged, with the rise of Thatcherism, to the Brixton riots just down the road” and that “there were many people of that time who were attracted to extreme groups on both sides of the debate”.

Now, leading in the polls and seemingly even on the way to Downing Street, Farage is definite that he said nothing antisemitic or racist as a young man.

Lihou, who said he had been moved to put his name to his testimony by Farage’s political success, said: “Nigel Farage has said, oh, you know, ‘I said some outrageous things, but none of them racist’. That’s absolute rubbish. It just isn’t the case.

“I am talking today because I am worried. He’s a charismatic guy. There’s no doubt about that. A bit like Boris Johnson, it’s very easy to find him an amiable rogue. And obviously a lot of people who feel that they can identify with that just get enchanted by that message, and therefore more and more people do.”

In Lihou’s view, Farage is “enabling people to be basically openly racist”. Lihou highlighted the Reform politician who said “all these black people make me sick”. He fears this kind of language has “become normal … And that’s the thing that, I suppose: [Farage] is the personification of this.”

Lihou is not the only one who claims to recall Ettedgui’s treatment at the hands of a young Farage.

“[Farage] certainly made comments to the Jewish guy in that class, Peter Ettedgui,” said Martin Rosell, who was in Farage’s year and who is now the chair of the Liberal Democrats in Salisbury.

“Comments like, under his breath, sort of ‘Jew’, that’s that type of … and comments about how they ‘missed you’, that sort of thing. He was noticeably more of those times than the rest. He was known for it across the school.”