The 55-year-old leader of the opposition suffered his first attack at his central London flat.

He had a second heart attack in the ambulance on the way to hospital and was pronounced dead at 0915 BST.

He leaves behind his wife, Elizabeth, and three daughters, all in their twenties.

The news comes as a shock to his party and the nation.

He was regarded as a man of integrity - decent and honest and was widely expected to lead Labour to victory at the next general election and become prime minister.

Senior politicians from all parties have paid tribute to Mr Smith and today's sitting of the House of Commons has been suspended as a mark of respect.

John Smith trained as a barrister and entered Parliament in 1970 as a Labour member for North Lanarkshire, Scotland. He served as secretary for trade in 1970 and subsequently as Labour spokesperson on economic and industrial issues, developing a reputation as a moderate.

After the Conservative election victory two years ago, he took over from Neil Kinnock as party leader and set about unifying the left and right factions of Labour.

Family man

Mr Smith was devoted to his family and was determined to spend as many weekends as possible at his home in Morningside, Edinburgh, but this made for a punishing public regimen.

It took its toll on a man who had already had one heart attack back in 1988.

The deputy party leader Margaret Beckett is interim party leader until a successor is chosen. Home Affairs spokesman Tony Blair is favourite to win the leadership and Gordon Brown, Robin Cook and John Prescott are expected to stand too.

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