Sir Ranulph Fiennes has issued a veiled threat to those who bullied him at Eton 50 years ago that they should watch their backs in case he decides to take revenge.

The polar explorer, mountaineer and former SAS explosives expert suggested that he had contemplated settling old scores with his tormentors, who taunted him remorselessly for three years when he was in his teens.

He dropped the hint as he described how he took up boxing at school to cultivate a more macho reputation because he was victimised for having a “pretty boy” image. “It was [a reaction] to being pretty, trying to be aggressive and trying to be unpretty, and big,” he said in an interview with Mark Lawson on BBC Four. “Boxing seemed to be the right answer, and it worked pretty well, I think.”

Asked whether he ever got to “sort out” his bullies, he said: “I never did do, no. You know the stories you read about people who get their own back 60 years later, so there’s still a chance ... I know who they are.”

Sir Ranulph, 65, who this year became the first British pensioner to reach the summit of Mount Everest, said that he also had a clear memory of the prefects who meted out corporal punishment at the public school.

Asked whether he had met any of his fellow pupils from Eton in later life, he said: “I got beaten by the prefects in my house, once by Jonathan Aitken, but I’ve met him since. There’s nothing wrong with him, and [he] only went to nick [prison] briefly.”

The baronet, who has the full name of Ranulph Twisleton-Wykeham-Fiennes, has previously said that none of the hardships he has suffered in his polar explorations has ever come close to the misery that he suffered as a schoolboy, even though he was bullied verbally rather than physically.

“Aged 13, I seriously considered suicide,” he said. “The very thought of escape from the stares, the sneers and the sniggers was a help. I would lie tearful in bed planning the death notes denouncing the worst culprits ... My self-confidence ... had reached an all-time low and I was never again comfortable in static social situations where people sit and banter.”

Martyn Lewis, the newsreader-turned-businessman who also suffered from bullying at school, said that Sir Ranulph had already had his revenge on his bullies by becoming visibly successful. “I’m sure that he was joking [about getting his own back], but it’s helpful that we don’t know he was joking, because then the bullies won’t know,” he said. “In my view, there is only one way to get revenge on bullies. I think revenge in the physical sense is too direct and too easy. I think the best revenge is to be determined to do better than them.

“I know that every time I read the News at Ten they would think, ‘That’s the guy we bullied’.”

Mr Lewis said that his experience of being bullied inspired him to set up Youthnet, a charity that provides support for children and young adults including victims of bullying.

Sir Ranulph has said that one of his tactics to avoid being bullied was to scowl a lot and ignore his tormentors. The problem was eventually solved by the school, which dealt with the bullies without exposing his identity, after he told his mother. Mr Lewis escaped his tormentors when his parents transferred him to another school.

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