Former Prime Minister Harold Wilson sold private documents to fund his treatment | Harold Wilson

Former British Prime Minister Harold Wilson has agreed to sell his archive of private papers to help fund his treatment, official documents have revealed.

Documents released by the National Archives and identified by the BBC show that Lord Wilson had originally planned to sell the collection to McMaster University in Hamilton, Canada, for £212,500, the equivalent of around £700,000 in today’s money.

Wilson, who was twice Labour prime minister, from 1964 to 1970 and again from 1974 to 1976, suffered from Alzheimer’s disease and required “continuous care, the costs of which are high and will increase”, according to a document. He died in 1995.

The proposal to sell the newspapers abroad caused concern among senior figures in Margaret Thatcher’s government.

In early January 1990, Cabinet Secretary Sir Robin Butler wrote that Wilson’s former secretary, Lady Falkender, was “orchestrating a proposal” to create an archive for the former prime minister’s papers in Canada.

Part of the proceeds would be used to support Lord and Lady Wilson, who were “now not very well off”, as Butler’s predecessor, Lord Armstrong, had reported.

McMaster University wanted the archives to include documents from Wilson’s time on the 10th floor.

Butler believed it would cause “public unease” if the newspapers left the country, while Andrew Turnbull, Thatcher’s principal private secretary, said he was unhappy with the “politics/morality” of such an idea.

“Although they are formally Lord Wilson’s private papers,” he wrote in March 1990, “they are part of our history and, it will be said, they are not really his to be ‘sold’.”

The Cabinet Office was informed that there was no legal obstacle to the sale – but by July 1991 an alternative solution had been found.

The Wilson Archive trustees had found anonymous donors who would fund the purchase of the papers by the Bodleian Library in Oxford, with the money going into a fund set up for the Wilsons. The papers would then remain in a secure location in the UK.