Sir Denis Thatcher complained just months before his death that John Major had been a "ghastly" Prime Minister and that the Tory Party would have been much better off if he had lost the 1992 general election.
In a televised interview to be screened this Sunday, Sir Denis attacked the "treachery" of senior Conservatives which brought about his wife's downfall 13 years ago.
Baroness Thatcher also told the Channel 4 programme Married to Maggie: Denis Thatcher's Story that she would "never forgive" Tory MPs for holding a leadership vote while she was in Paris.
Interviewed by his daughter Carol last October, Sir Denis, who died in June aged 88, revealed for the first time the depth of his loathing of Mr Major's time in office.
The decision by Tory MPs to ditch Mrs Thatcher had appalled millions of people all over the country, he said. "That's what upset them. Treachery. And it would have been a very, very good thing if the next election after Margaret went we had lost," he said.
"If Major had lost, we wouldn't have had the disaster we've got now. He was a ghastly Prime Minister, more people deserted our party. The whole of the situation of the Conservative Party today springs from that night when they dismissed the best Prime Minister the country had had since Churchill."
Sir Denis recalled that in 1990 his wife was ready to leave Downing Street. "I think she was ready to go.And go at the top. Undefeated," he said.
Lady Thatcher revealed the continuing depth of her bitterness at the first leadership ballot, which she failed to win convincingly. She was subsequently persuaded not to contest a second ballot. She said: "What I will never forgive is that I was away and there was a vote on whether I should continue. It was the most difficult evening of my life. I shall never forget that, and I shall never forgive."Reuse content