The former Prime Minister said she wanted to see the Queen remain on the throne until at least 2012 to celebrate her 60th anniversary.
'The best thing that can happen to this country is that she should celebrate her diamond jubilee in 2012.
'It is my great ambition that her record in number of years will exceed that of Queen Victoria. It will add to our stability and our prestige in the world.'
Lady Thatcher, who once promised to 'go on and on and on', before being deposed, added: 'I want to be there to see it, cheering her on the Mall with my grandchildren.'
Lady Thatcher's remarks, in the Sunday Telegraph, echo the feelings of government ministers who hope the Queen's longevity will settle the controversy over whether Prince Charles or his son William should succeed, after the breakdown of his marriage to the Princess of Wales.
'The Windsors are long-lived. Just look at the Queen Mother. There's every chance the Queen will go on until a ripe old age,' one minister said.
While speculation continued that the Prince of Wales would divorce in two years, opinion polls at the weekend suggested that public opinion would be against the Princess of Wales becoming Queen.
A Sunday Express/ICM poll of more than 1,000 found that the Princess would face disapproval as Queen by 56 per cent; 49 per cent wanted Prince William to be the next king. Only 45 per cent wanted Prince Charles to claim the throne.
Lord McAlpine, the former Conservative Party treasurer, accused the Princess of Wales of fighting a propaganda campaign against the Royal family. 'She cannot be allowed to enjoy the spoils of that victory,' he said in the Sunday Express, which also reported that the Establishment was putting the blame on her.
However, its ICM poll found that 56 per cent of the public blame Prince Charles for the breakup and only 11 per cent blame the Princess.