Memoirs written by Judith Chaplin, who worked for Mr Major when he was Chancellor of the Exchequer and Prime Minister between 1989 and 1992, also reveal how Mr Major described Mrs Thatcher as "mad", "loopy" and "emotional". The diaries have emerged just weeks before the release of Mr Major's autobiography, and both publications will ensure that his legacy as Tory Prime Minister will come under closer scrutiny.
During her time in Downing Street, Ms Chaplin was a dominant figure in what became known as his "kitchen cabinet", and became Tory MP for Newbury in the 1992 election. She died the following year during a routine operation.
The diaries, published in The Sunday Telegraph, show the"grey man" of British politics was an insecure pragmatist, concerned only with his own position. On the day after Mr Major became Prime Minister in November 1990, Ms Chaplin reflected: "He is certainly tough enough. It is possible to understand if you recognise that every decision is taken on how it affects him and promotes him." By March 1991 Ms Chaplin was concerned about the direction, or lack of it, of the Major government. "It is worrying that he has no underlying conviction about the way he wants policies to go - pragmatic to a fault," she wrote.
And the "nice man" image also takes a patronising, back-handed blow. "JM is a nice man but pitch-forked in with no clear principles about what he is trying to achieve ... It makes me feel nervous."
The following month Ms Chaplin wrote about the amount of time wasted in dealing with what the media has said about him. "He cannot bear to be criticised and takes it as a personal slight: he is obsessed by his image and will have to get a tougher skin," she wrote.
But it was when this criticism came from Mrs Thatcher that his reactions became the most extreme. After her apparent coining of the phrase "grey man" in June 1991 and attacking him for having "no ideas", although she denied saying it, he told his press secretary: "I want her isolated, I want her destroyed."
The diaries continue: "He [Mr Major] has been to see her but obviously says one thing to her face and something different behind her back. He often makes foul remarks about her - `mad', `loopy', `emotional' - very unattractive considering what he owes her."