More or Less this week takes a long look at a stark fact. The richest social class in Britain, the top 20%, live on average about seven-and-a-half years longer than the poorest.
But why? And what can be done about it?
The causes are not always as obvious as they seem.
Diet, for example, seems not to matter quite as much as we might think. Being overweight turns out to be associated with low social class for women, but not really for men.
And in any case, being a bit overweight does not seem to make much difference to life expectancy, although obesity does.
One factor, though, does stand out.
Smoking among men in the top class is about 2%. In the bottom class it is about 40%. And this is thought to cost them about three-and-a-half to four years of life.
But when we investigated efforts to encourage the changes of lifestyle that are thought to make the difference, we discovered another problem.
Even when we know what to do, reaching the people who could most benefit from it, proves extraordinarily tough.
Find out what can be done, and what cannot, in this week's More or Less.
Presenter: Andrew Dilnot
Producer: Michael Blastland
BBC Radio 4's More or Less was broadcast on Monday, 28 May, 2007 at 1630 BST.
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