Margaret Thatcher once refused to share a flight to Washington with a giant panda

Margaret Thatcher once refused to share a plane with London Zoo's giant panda, newly-released National Archive files revealed.

Mrs Thatcher did not believe pandas make "happy omens" for travelling politicians.

Her surprising aversion emerged in January 1981 after Lord Zuckerman, president of the London Zoological Society, suggested that the male panda named Chia-Chia could share the former Prime Minister's Concorde flight to Washington.

It was hoped the male panda could mate with a female panda that China had given to the United States.

Lord Zuckerman seized upon the idea as an opportunity to generate some much-needed publicity for the cash-strapped zoo.

And he immediately contacted Downing Street to see if the Prime Minister would like to preside over the handover.

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, however, was having none of 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 National Archives in Kew, London, contains more than 11 million historical Government and public records. Government records selected for permanent preservation are released to the collection after 30 years.

Chia-Chia left London Zoo in 1988 when he was sent to Mexico City Zoo on a permanent breeding loan.