Nigel Farage is under pressure to explain a letter from his schooldays in which teachers branded the future Ukip leader a “fascist” and “racist”.

According to the letter written in 1981 by a young English teacher at the private Dulwich College in south London, plans to appoint Mr Farage as a prefect were bitterly opposed.

The letter, revealed by Channel 4 News tonight, was reportedly sent by Chloe Deakin to the college's then headmaster, David Emms, and included an account of what was said by staff at their annual meeting to discuss prefects.

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One teacher was claimed to have said Mr Farage was “a fascist, but that was no reason why he would not make a good prefect”.

The letter added: “Another colleague, who teaches the boy, described his publicly professed racist and neo-fascist views; and he cited a particular incident in which Farage was so offensive to a boy in his set, that he had to be removed from the lesson.”

According to another teacher, at a Combined Cadet Force camp organised by the college, Mr Farage and others had marched through a Sussex village “shouting Hitler-youth songs”.

Mr Farage told Channel 4 News that he had been shown a copy of the letter. He admitted to being a “troublemaker” at school who “wound people up”.

“I did say things that would offend deeply,” he said. “And there were certainly two or three members of the English staff I made arguments against that I didn't necessarily believe in. But any accusation I was ever involved in far right politics is utterly untrue.”

He described the claims about Hitler Youth songs as “silly” and added: “I don't know any Hitler youth songs, in English or German.”