His parents separated 12 years ago - after which he refused to speak to his father and now lives with his mother. On leaving Millfield he joined the Guards and saw service during the Gulf conflict, where he commanded a battle group which, during the liberation of Kuwait, reportedly destroyed 300 Iraqi tanks and took 8,000 prisoners. After failing his major's exam - he was only an acting major - he retired with a lump sum, believed to be worth pounds 40,000.
The tabloid newspapers started to take a strong interest in him after publication of the 'squidgy tapes' in August 1992. These were said to be telephone conversations between himself and the Princess of Wales.
The tabloids then discovered that he had a reputation as a ladies man. His main problem, one friend said, 'is that in finding his way through life he keeps his compass in his trousers'. He was said to have confided in one former girlfriend: 'I ought to tell you that I have known at least 50 women in the past six years.'
He was reported by the Evening Standard as telling another friend: 'I have always been a bit of a sucker for blondes. A girl can be many things, but if she's not beautiful then she's not for me. I am very choosy. It's like looking for a good horse.'
He first met the Princess of Wales in 1987 at a society party. She asked him to teach her to ride - she had earlier lost her nerve. Their friendship grew and they allegedly became romantically entwined. In the 'squidgy tapes', the princess, referring to him, said: 'Entirely dressed him from head to foot, that man. Cost me quite a bit.'
During the Gulf war they kept in close contact and, according to some newspapers yesterday, extracts of their letters form the core of the book. He was alleged to have produced some of the letters during his meetings with the News of the World, but concealed details.
In yesterday's News of the World, Major Hewitt is quoted as saying the princess often stayed with him secretly in Devon and he would see her at Kensington Palace while the Prince of Wales was away.
He claimed to have visited her at Highgrove. 'I was madly in love with her and helped her in so many ways,' he is reported as saying. 'I advised her on what clothes she should wear, how to deal with the press and even helped her practise her public speaking.'
Yesterday's revelations are not the first he has made regarding the Princess of Wales. He made a string of insinuations in February and sold a story to Express Newspapers for pounds 100,000.
He is said to no longer have money or property, and lives with his mother or stays with friends in London. He invested money from the sale of previous newspaper interviews in an unsuccessful golf range.
If the allegations are true Mr Hewitt may face the death penalty for treason. By statute a person is guilty if they violate 'the wife of the sovereign's eldest son and heir'.