Former Commons leader Lord Newton of Braintree has died at the age of 74, his family announced on Monday.
Tony Newton became Tory MP for Braintree, Essex, in 1974, holding on to the seat for 23 years before being made a peer.
He began his Government career in the Whips' office and held a number of ministerial roles under Margaret Thatcher.
They included a stint as health minister, an area in which he retained a keen interest throughout his political career, contributing to debates in the Upper Chamber over the controversial Health and Social Care Bill in recent weeks.
In 1989 he was made social security secretary and three years later was appointed Lord President of the Council and Leader of the House of Commons.
Lord Newton, who died on Sunday in Colchester Hospital following a long illness, is survived by wife Patricia, two daughters, Polly and Jessica, three stepchildren, Robin, Emma and Sukie, and 10 grandchildren.
In a statement, his family said: "In spite of his worsening health, he was determined to carry on contributing to public life right up until the last few days.
"He was a remarkable man and we will miss him very much."
Lord Newton was said to be the only person, apart from the couple themselves, who was aware of the affair between Edwina Currie and John Major.
It was a secret which he honoured. If word had ever got out, it is almost certain that Mr Major would never have become prime minister.
Mrs Currie and Mr Major - as he then was - needed one, just one, trustworthy person to be aware of their relationship in the event of a crisis in the Commons when they had to be brought back to the House for a vote.
Despite harbouring this explosive secret alone for so many years, until Mrs Currie revealed it in a book, Lord Newton steered clear of all the sleaze which dominated and tarnished John Major's administration.
Indeed, he was once jocularly dubbed "a mud-free Tory who could rise clean to the top".
Tony Newton entered the House of Commons in 1974 as MP for Braintree, a seat he represented until 1997 when he became Lord Newton of Braintree.
Educated at Trinity College, Oxford, he then spent 14 years at the Conservative Central Office research department.
His stay there was interrupted by an unsuccessful attempt in 1970 to capture the Labour stronghold of Sheffield Brightside.
After his election in 1974, he became junior social security minister in 1982 and was promoted to minister for social security and the disabled in 1984 before switching to health minister in 1986.
He was appointed social security secretary in 1989, and quickly gained a reputation as a doughty fighter for a department whose budget demands inevitably brought it into regular behind-the-scenes conflict with the Treasury.
Previously, as chancellor of the Duchy of Lancaster, Mr Newton co-ordinated Mrs Thatcher's inner-city policies before he became lord president of the council and leader of the House of Commons in 1992.
His first marriage, by which he had two daughters, ended in divorce. He remarried in 1986.