What is the real danger of sunbathing? I’ve heard doctors arguing that it prevents some cancers as well as causing them.

We need to have sunlight on our skins – the problem comes when we get burnt. The evidence that sunburn causes all three types of skin cancer – we call them basal and squamous cell cancer and melanoma – comes from Australian and Scottish studies. The commonest sites for melanomas, in particular, are on the trunk in men and on the legs in women, sites most exposed to the sun. There is evidence, however, that regular but non-burning sun exposure (which boosts vitamin D production) helps to prevent internal cancers such as breast, prostate, pancreas and colon. The Australians, who have the highest skin cancer rates in the world, disagree with this: they say that if the internal cancer prevention story were true, they would have far fewer of them than elsewhere, and they don’t. I can only add, as a British GP, that we need a lot more sun here before we have to cover up. Nevertheless we shouldn’t allow the sun to burn us, and particularly our children.