Francis Pym, Thatcher's enemy within, dies aged 86

Lord Pym, who served as Foreign Secretary during the Falklands War and fell out comprehensively with Margaret Thatcher, has died after a long illness. He was 86.

As Francis Pym, he was promoted when the former foreign secretary Lord Carrington resigned due to his department's failure to foresee the Argentine occupation of the Falkland Islands.

Former colleagues paid tribute to a man who was, in effect, born into the Conservative Party, but who belonged to the pre-1980 era and was unable to form a working relationship with Mrs Thatcher.

Gordon Brown led the tributes to Lord Pym, saying: "He was a distinguished parliamentarian who served his country for more than 45 years in the House of Commons and in the House of Lords."

"He was a man of great decency and principle and everyone will remember him as a good man who always did what he thought was right for his country."

The former prime minister Sir John Major praised him as a "neighbour, mentor, friend", who "served his country in an exemplary fashion, in war and peace, in the Commons and the Lords".

In April 1982, while the naval task force was making its way to the South Atlantic to reclaim the islands, Mr Pym was dispatched to Washington for talks with the US Secretary of State, Alexander Haig, who was determined that two of America's major allies should not go to war.

Mr Pym appears to have privately agreed with Mr Haig that they needed a way to avoid fighting. Between them they drew up draft proposals which Mr Pym took back to show to Mrs Thatcher. "I can only describe the document which he brought back as conditional surrender," she wrote in her memoirs. "They would rob the Falklanders of their freedom and Britain of her honour and respect. Francis disagreed. We were at loggerheads."

Mr Pym compounded the offence during the 1983 election campaign, which gave the Conservatives their biggest victory since the war, when he warned that an overwhelming majority for a party was not necessarily good for democracy.

If anyone was in doubt about the tense relations between the Prime Minister and her Foreign Secretary, they were put on show for all to see during the campaign, when Mr Pym was asked a question at a press conference about the possibility of negotiating with the Argentinians about the future of the now recaptured islands.

He gave a diplomat's reply, which infuriated Mrs Thatcher, who was sitting almost next to him. In front the world's press, she flatly contradicted him to say that there would be no negotiating over the islands' sovereignty. Once the election was over, she fired him, though she sought to sugar the pill by suggesting that he run for the vacant office of Speaker. He chose not to, and retired from the Commons to resume his business career, and enter the House of Lords in 1987.

It was an unfortunate end to a career of a man who background and political philosophy was perfectly in tune with what the Conservative Party as it used to be, before the rise of Thatcher.

A descendant of a 17th-century Commons Speaker, he was educated at Eton and Cambridge University, and served as a captain in the 9th Royal Lancers in north Africa and Italy during the Second World War, receiving the Military Cross twice. After the war he went into business as a manager of a firm that made tents.

He won a by-election in Cambridgeshire, near to his family's Bedford seat, in 1961, and – like his father – was appointed a government whip, serving for 11 years under three successive Conservative prime ministers, Macmillan, Douglas-Home and Heath.

He also served in Mrs Thatcher's Cabinet as Defence Secretary and Leader of the House. Lord Pym's family said in a statement: "Lady Pym and her family are extremely sad to announce the death of her beloved husband Lord Pym after a prolonged illness. Francis died at home on 7 March just after midnight."

A private family funeral will take place shortly.