Labour leaders past and present are mourning the death of millionaire Nigel Doughty, the owner of Nottingham Forest and a major party donor.

The football club said Mr Doughty was found in the gym at his Lincolnshire house.

It said in a statement: "It is with enormous sadness that Nottingham Forest announce the death of the club's owner Nigel Doughty. Mr Doughty, who was 54, was found dead earlier today in his gym at his home in Skillington, Lincolnshire."

Labour leader Ed Miliband said: "I am shocked and saddened to hear of Nigel Doughty's death. I was with him only a week ago and he was full of life, enthusiasm and vigour.

"He was a kind, generous man with a deep desire to make the world a better place. My heart goes out to his wife Lucy and his children. We mourn his death deeply and will sorely miss him."

Mr Doughty gave at least £3.5 million to the Labour Party over the last seven years and was on the board of assistant treasurers of the party.

Former prime minister Gordon Brown said: "Nigel Doughty will be remembered as a gentle giant, a good soft spoken man with a deep commitment to public service who, from his great success in business, became one of our country's most generous benefactors.

"For all his life he was loyal to all the causes that he had grown up with - his love for his team Nottingham Forest, the Labour Party, of which he was a life long supporter, and charitable causes that benefited from his generosity. My thoughts are with his widow Lucy and his whole family whom he loved so much."

Mr Doughty, who saved the Reds from administration when he bought the club for £11 million in 1999, had invested almost £100 million of his personal fortune in the club.

A spokesman for Lincolnshire Police said: "At 2.13pm we received a call reporting the death of a male at an address in Skillington, Grantham. There are no suspicious circumstances surrounding the death and the matter has been passed on to the coroner."