Tributes have been pouring in for Sir Denis Thatcher, the husband of former Prime Minister Margaret Thatcher.
Baroness Thatcher hailed her husband's "shrewd advice"
Sir Denis died in a London hospital on Thursday morning with his wife of more than 50 years at his bedside.
Tony Blair and Iain Duncan Smith have been among those saluting Sir Denis' influence during Baroness Thatcher's premiership and praising his business sense and courtesy.
The 88-year-old, who had heart surgery in January this year, returned to hospital after feeling unwell two weeks ago.
A spokesman for the Thatcher family said on Thursday: "It is with deep sadness that we have to announce that Sir Denis Thatcher passed away peacefully this morning in the Lister Hospital after a short illness."
The Thatchers' children Mark and Carol were also at Sir Denis' bedside when he died.
The union flag at Conservative Central Office in London was lowered on Thursday in a mark of respect.
Although he had enjoyed success as a millionaire businessman, Sir Denis' public fame owed most to his marriage to Margaret Thatcher.
And she often spoke of her gratitude for his support.
Writing in her autobiography, The Downing Street Years, she said: "I could never have been prime minister for more than eleven years without Denis by my side.
"He was a fund of shrewd advice and penetrating comment. And he very sensibly saved these for me rather than the outside world."
Conservative leader Iain Duncan Smith said he was devastated by the death of "one of the most decent, determined and kind people that we have known".
"In a world that so often seems to have lost its manners, Denis Thatcher represented so much of what was best in the wartime generation," he continued.
Mr Duncan Smith said Sir Denis had played a "vital role" in his wife's success, as well as being a successful businessman and brave soldier in his own right.
Baroness Thatcher said she could not have done without Sir Denis
Tory MP John Whittingdale, who used to be Baroness Thatcher's political secretary, said Sir Denis and was held in enormous respect and affection across the country.
"He made a huge contribution to Mrs Thatcher's political career. He was behind the scenes all the time giving her support and I think she and her family will miss him dreadfully," he said.
Speaking at a news conference with Russian President Vladimir Putin, Tony Blair said: "Sir Denis was a kind and generous-hearted man, a real gentleman who had many friends here and abroad.
"I know how much he meant to Margaret Thatcher and to the whole family and I know whatever part of the political spectrum we are on, we would like to send our deepest condolences and sympathy to the Thatcher family."
The last Tory prime minister, John Major, said Sir Denis had a clear set of attitudes which he told his wife in private.
Mr Major added: "He gave Margaret a hinterland, particularly during the difficult days of being prime minister, which otherwise she would not have had. I think that was immensely valuable."
There was praise too from close friend Bill Deedes, the former Daily Telegraph editor who was recipient of Sir Denis' fictional Dear Bill letters in Private Eye.
"There were hidden depths to Denis Thatcher, he was very self-effacing," he said.
"He kept himself out of the limelight and he concealed his virtues for his friends as well as everyone else."
Lord Deedes said Sir Denis had been a "bulwark" to Baroness Thatcher and was able to provide a calmer outlook at times.
Sir Denis underwent a heart by-pass in January, with doctors calling the operation a "complete success".
But he was readmitted to the Royal Brompton Hospital for tests earlier this month and later transferred to the Lister Hospital.
He was said to have been in good spirits and had received several visits from Lady Thatcher.
Sir Denis is said to have been the key influence in persuading his wife to bow out of public speaking after she suffered a series of slight strokes.
She has defied doctors, however, by attending a number of functions.
Sir Bernard Ingham, Baroness Thatcher's former press secretary said: "I am extremely sad that he has died. I have very many fond memories of him as the prime minister's consort and husband.
"He was extremely loyal and supportive in that position. He was in fact a manifest role model for any prime minister's consort."