One picture can define a premiership. There is that famous shot of Margaret Thatcher, wiping away a tear as she departed No 10 for the last time – betraying an emotion she never showed while in office.
The final moments of Gordon Brown's tenure were captured in an extraordinary image, as he posed for the camera with his family inside No 10, an arm round three-year-old Fraser perched on a desk, moments before stepping out into the street to announce his resignation.
The picture has been much commented on. But one poignant aspect has been missed. Mr Brown described his role as prime minister as "the second most important job I will ever have", after that of husband and father. What is the greatest fear of a father (or mother)? That their children will die before them.
Mr Brown, at 57, is no longer young. Even so, it will be touch and go whether he outlives Fraser, who has cystic fibrosis, the commonest inherited condition in the West. The gene defect that causes the condition thickens secretions throughout the body, making them dry and gluey, and has a lethal effect on the lungs, whose airways fill with sticky mucus.
There is no sign of this in the boisterous child in the photograph. But the future Fraser can look forward to will depend to a critical extent on a neglected but crucial aspect of medical care: expectation.
In the 1950s, a child born with cystic fibrosis lived on average until the age of three. Today, thanks to improvements in care, that has extended to the mid-30s. Most patients are now cared for in specialist centres that have built up years of experience in managing the condition.
Yet there remain, as US surgeon and writer Atul Gawande noted in his 2007 book Better, shocking gaps in performance. The best centre in the US, Fairview Children's Hospital in Minneapolis, had a life expectancy 50 per cent better than the average. It's oldest patient was 67.
What accounts for the difference? The best centres were not using different drugs or treatments – they were just applying them better. Successful treatment of cystic fibrosis requires extraordinary commitment, attention to detail and a refusal to accept second best in order to maintain peak lung function. While the average centre might accept lung function at 75 per cent of normal, at Fairview they were not content with less than 100 per cent. They questioned everything when standards slipped, rather than accepting it as an inevitably by-product of the illness. Expectation was the key.
The treatment Fraser and his fellow patients receives will provide a touchstone for the performance of the NHS. Instead of searching for the easy fix, the miracle cure that will solve a problem, it needs to focus – in these straitened times – on diligence: doing what it has always done but doing it better. As Gawande said, the reality is that most clinics and most doctors will be average. That we must accept. What is troubling is not just being average, but settling for it.