“They’re both really committed to the country.
“They both have a strong Christian faith.
“They’re both girls of the war generation who switch the lights off when they leave a room.
“But then they had such different ideas about running the country.”
The Queen’s relationship with the Prime Minister is crucial, as the pair meet weekly to discuss the politics of the day.
Boris Johnson is her 14th Prime Minister – Mrs Thatcher was her eighth and longest-serving.
Unearthed footage from a 1992 documentary shows Her Majesty speaking French as she mingled at a Palace drinks reception the previous year.
Mrs Thatcher and Princess Diana were among the attendees.
The clip, however, does not show the Queen speaking to the then-PM Mrs Thatcher.
Princess Margaret, the Queen’s sister, told a Channel 5 documentary that it was the only time she had seen her cry.
She said: “I’ve only seen my sister cry once.
“It was when the Press put all the articles about her not getting on with Mrs Thatcher.”
The documentary later revealed that Mrs Thatcher would rush off to have a glass of whisky to recover from her weekly Palace meetings, such were her nerves at facing the Queen.
Mrs Thatcher’s Principal Private Secretary, Lord Robin Butler, recalled: “Mrs Thatcher was in awe of the Queen.
“Like a lot of assertive people, she was lacking in confidence.”
The Queen is reported to have once lost her cool with the Prime Minister.
When staying at Balmoral, Her Majesty allegedly said: “Can’t that woman just sit down?”
Despite the seemingly tense relationship between the two, Mrs Thatcher never lost her respect for the monarchy.
Her former Chief Press Secretary, Bernard Ingham, told Amazon Prime documentary ‘The Queen and her Prime Ministers’ she was perhaps “too punctual” when it came to her weekly meetings with the monarch.
The narrator of the documentary said: “Whenever she went to see the Queen, Mrs Thatcher always arrived a quarter of an hour too early for her weekly audience and every week the Queen let her wait for 15 minutes.”
It seems, however, that their relationship mellowed over time.
BBC broadcaster Michael Cockerell said they did eventually “get on”, and “I think Mrs Thatcher came to value the advice the Queen gave her”.
Royal biographer Hugo Vickers echoed this. He added the Queen was “very upset” by the “horrible” way in which Mrs Thatcher was ousted from Downing Street by rivals within the Conservative Party.
This year’s invitation is believed to have been extended to Boris Johnson, his pregnant wife Carrie and their son Wilfred.
However, they are yet to travel north of the border, and the ongoing Afghanistan crisis could make it more difficult for Mr Johnson to do so.
Downing Street did not comment on whether Mr Johnson will travel to Scotland to meet Her Majesty in the coming weeks.
Source: EXPRESS CO UK