Papers released by the National Archive have revealed Margaret Thatcher once refused to fly on the same plane as a panda, as she thought it was not a "happy omen" for travelling politicians.
When the Smithsonian Institute requested the loan of London Zoo's male panda, Chia Chia, to mate with their female at the Washington venue in January 1981, it was thought the move could aid Anglo-American relations.
The president of the London Zoological Society, Lord Zuckerman, suggested the idea that Mrs Thatcher would like to conduct the handover of the panda personally in order to generate some publicity for the zoo.
The cabinet secretary Sir Robert Armstrong wrote: "Lord Zuckerman sees this as a signal demonstration of the special relationship and would be very happy to time the announcement of the loan or the delivery of the panda in any way that the prime minister thought would be most likely to benefit Anglo-American relations.
"He even suggested that the Prime Minister might like to take the panda in the back of her Concorde, when she goes to Washington next month."
Mrs Thatcher was less keen on the idea and quickly put a stop to it. Her private secretary, Clive Whitmore replied: "She has commented that she is not taking a panda with her - 'Pandas and politicians are not happy omens!'"
She added in a handwritten aside: "Lord Z knows more about pandas than I do - I am sure he can arrange these things."
The former prime minister also had heated argument with her successor, John Major, over his handling of the economy, the released papers show.
Mrs Thatcher warned that "excessively high" interest rates risked pushing the economy into recession.
Mrs Thatcher had only weeks before backed her protege to succeed her as prime minister but the meeting in Mr Major's private office in January 1991 resulted in her suggesting he was on the verge of committing an "historic error" with the economy.
The papers show how their relationship deteriorated quickly after she departed No.10 in November 1990, as Mrs Thatcher became angered by his scrapping of the "poll tax", even though it was a key element in her downfall.
She even compared the position to Winston Churchill's calamitous decision as chancellor in 1925 to return Britain to the gold standard - a move that led to deflation, mass unemployment and the General Strike.
"Mrs Thatcher said conditions on the economy were very tough indeed," the official minute of the meeting noted. "She believed that there was a danger of repeating Winston Churchill's historic error."
Mr Major responded to criticism from his predecessor by saying the situation "was not remotely comparable". Relations between the two continued along similar lines for the remainder of Mr Major's tenure.