Amid the constant news barrage of bad banks and billion-sum bail-outs, the story of a personal tragedy marks a reality check. Last Wednesday, the sudden death of a six-year-old disabled boy brought the British parliament momentarily to a standstill. Party politics were put aside and prime minister's question time cancelled as Gordon Brown sympathised with his bereaved opposite number, David Cameron.

The unexpected death of the Conservative Party leader's young disabled son Ivan, who suffered from epilepsy and cerebral palsy, had
come as a huge shock to his parents, even though the little boy had had numerous scares in the past with life-threatening fits. Gordon Brown, whose own newborn daughter died seven years ago, and whose son, Fraser, has cystic fibrosis, was visibly moved as he offered condolences in the House of Commons. "The death of a child is an unbearable sorrow no parents should have to endure."

On the same day as news emerged of his son's death, The Guardian newspaper had already gone to press with a seven-page spread speculating on Cameron's standing as political leader and, very likely, Britain's next prime minister. He's not considered a conventional Conservative and yet has all the true blue credentials of the old establishment Tory. Educated at Eton and Oxford, he is a top-drawer toff, the descendant of three prominent Tory MPs. He grew up in a Berkshire rectory with a swimming pool in the walled gardens. A former girlfriend of 'young Dave' describes summer holidays straight out of Enid Blyton. "There was a constant supply of homemade lemonade, fresh sandwiches and chocolate cake."

Being the son of a stockbroker is not exactly something to shout about these days, but Cameron has always tried to play down that privileged background to prove he's a cool, classless guy. With mixed results. He claims to have introduced the man of the moment, Barack Obama, to the music of Radiohead and The Smiths when the two met early last year in Westminster. Obama is said to have later described Cameron as a "lightweight". Which may refer to the Tory leader's pitch to be middle-class everyman. Or that he gave Obama the gift of a Lily Allen CD.

During his successful bid for the party leadership in 2005, his informal discarding of tie and jacket saw him described as a 'Tony Blair for the Tories', a member of swinging young London conservatives dubbed by the press as the 'Notting Hill Set'. Cameron's mantra is "freedom and individual responsibility". He insists the old party lines of Labour on the left and Conservatives on the right are no longer so clear cut. "I believe there is such a thing as society," he once said. "I just think it's different from the state." It's that view that older Tory MPs see as his abandonment of traditional Conservatism.

In education terms at least, public schoolboy Cameron has more in common with the recent Labour party leadership (his headmaster at Eton had previously been Tony Blair's housemaster at Frettes public school). After Oxford, he worked in the Conservative Research Department, quickly rising through party ranks. In archive footage of Norman Lamont on Black Wednesday – the day Britain pulled out of the European Exchange Rate Mechanism – a figure can be spotted scuttling behind the scenes. It was the chancellor's young political aide, David Cameron. A subsequent seven-year stint as head of PR with ITV's Carlton left a bad impression among some members of the media. The Sun's business editor Ian King's caustic recollection is of a "poisonous, slippery individual". Jeff Randall, then of The Daily Telegraph said: "Cameron never gave a straight answer when dissemblance was a plausible alternative – which probably makes him perfectly suited for the role he now seeks: the next Tony Blair."

The ongoing criticism is that his blue-blooded heritage leaves Cameron lacking the common touch. When asked by GQ editor Dylan Jones if he was middle-class or upper class, he replied: "I suppose I'd describe myself as well off." He and his wife Samantha own a country house in his Oxfordshire constituency. They bought their second home, in west London, in 2006 for more than £1m – without needing a mortgage.

The most profound, un-Toryish, influence on Cameron's politics was said to be his son Ivan. About a week after the birth in April 2002, it became apparent that the little boy was seriously ill.

Cameron recalled the moment he and his wife Samantha were told their son had a rare neurological disorder, Ohtahara syndrome. "It changes your life, because there are all the wonders of the baby being born, and everything is so exciting, and suddenly this news hits you like a freight train."

Initially the couple looked after their son alone, but eventually his need for around-the-clock care led them to seek help from social services. The basement of their Kensington home was converted to a special bedroom to allow for special nursing care.

Unlike other Tory leaders, Cameron is a vocal supporter of the Labour party's greatest ever creation – the National Health Service. That contact with the NHS shaped his political views. "It [the NHS] brings you into contact with a whole world." He is an advocate for disabled children, while noting that "it's not nearly as tough for us as it is for some families".

The Cameron family coped with Ivan's illness by "keeping going with life. Some people are angels: they can just give up everything and care for their children 24/7. I think I'm a good father. But I'm a better father for being at work as well."

Just as his son's short life influenced his politics, his passing will also impact on the policies of the man widely predicted to be Britain's next prime minister.

CV

Born: October 1966, Kensington to Ian Donald Cameron and Mary Fleur Mount. Grew up near Newbury, Berkshire

Educated: Eton and Oxford, first class degree in Philosophy, Politics and Economics (1987)

Personal life: Married Samantha Sheffield, step-daughter of Viscount Astor, 1996; three children Ivan (6), Nancy (5), and Arthur (3)

In the news: Sudden death of his disabled son Ivan