Queen Camilla escaped being groped by a man on a train by whacking him with her shoe, according to a new book

The details - which Buckingham Palace has not made an official statement about - are recounted in Power and the Palace, written by Valentine Low, The Times newspaper's former royal editor.

Low writes in his book, serialised in The Sunday Times, that Queen Camilla told Boris Johnson, 61, about the attack whilst he was Mayor of London at a meeting in Clarence House in June 2008.

The author recounted speaking to Johnson's former communications director, Guto Harri, 59, who told Low that the former Prime Minister informed him about their meeting in Clarence House.

In an extract from the book, Harri said: "Boris was raving about her. They obviously got on like a house on fire. He was making guttural noises about how much he admired and liked her.

"But the serious conversation they had was about her being the victim of an attempted sexual assault when she was a schoolgirl.

"She was on a train going to Paddington - she was about 16, 17 - and some guy was moving his hand further and further ..."

Valentine wrote: "At that point, Johnson had asked what happened next. She replied, 'I did what my mother taught me to. I took off my shoe and whacked him in the nuts with the heel.

"Harri said, 'She was self-possessed enough when they arrived at Paddington to jump off the train, find a guy in uniform and say, 'That man just attacked me', and he was arrested."