There is something disturbing about Sydney when you see it, as it were, in the flesh. Australia's premier city sits astride a sparkling harbour under an azure sky.
There is the famed opera house and the magisterial Harbour Bridge linking the northern and southern shores. You see why estate agents promote Sydney as the city with the matchless lifestyle.
Now take a look at the people. They are pasty-faced. The clothes are grey and beige, the skin a pimply shade of pale. To anyone who has holidayed on the shores of the Mediterranean, with its smooth, olive-skinned peoples, this comes as a shock. Here, in one of the most sun-kissed cities of the world, the people look as though they live underground.
In a sense, many of them do. A generation of Australians has been raised to fear the sun, never venturing out without a hat, long-sleeved shirt and factor 30 sunblock. These people avoid the beach, keep their children covered head-to-toe in summer and go for regular check-ups in the ubiquitous skin cancer clinics.
This could be about to change. The Cancer Council Australia has issued new advice on the sun, which, some claim, amounts to a seismic shift in its thinking. After more than two decades of warning people to stay out of the sun, the new advice, to be published in The Medical Journal of Australia (MJA) this month, says that a little of it is essential for good health.
The reason for this change of heart is that a new problem has emerged in Australia: vitamin D deficiency. Vitamin D is made by the action of the sun on the skin and is essential for good bones, a healthy immune system and possibly also for protection against some forms of cancer.
Spelling out exactly what this means, the advice in the MJA says that, in Sydney and southern parts of Australia, people should expose their unprotected face, hands and arms to the sun for five to 10 minutes before 10am or after 3pm on most days of the week in summer to get adequate doses of vitamin D. In winter, they need two to three hours of exposure over a week.
Some people - the elderly, the housebound, people with dark skin or who wear enveloping clothes such as the burka - are at particular risk.
Bruce Armstrong, professor of public health at the University of Sydney, says: "It is a revolution. I have worked in public health and been preaching sun avoidance for 25 years. But what this statement says is that there are two sides to the story. You need to get enough vitamin D and you need protection from the sun. These two objectives are in conflict and we have to advise people how to do both."
Australia is the skin cancer capital of the world. Pale-skinned immigrants from northern Europe burned under the fierce southern skies and, over the latter half of the last century, as the fashion for tanning grew, cases of melanoma, the worst form of skin cancer, soared.
Among men in northern Queensland, the rate has risen to 51 cases per 100 000 population - 20 times higher than the rate in Scotland. In response, the country launched the world's most successful sun-avoidance strategy. The government's "slip, slap, slop" campaign in the 1980s - slip on a shirt, slap on a hat, slop on the sun cream - was copied around the globe.
On Bondi Beach, you can see how the advice has taken hold. While the stretch of golden sand is covered in bronzed bodies soaking up the sun, most of them are foreigners. The few Australians on the beach are well covered or smeared in sun cream.
Karon Caplan, 36, wearing a straw hat and ankle-length black dress, has brought her two children, aged three and four, to the paddling pool. Both are dressed in swimming costumes that cover them from the elbows to the knees and wear hats with flaps protecting their necks.
"I am pretty paranoid about the sun," she says. "I never go out without sunblock and both the kids are not allowed out at school without hats. If someone is burned red here they are probably from the UK."
"Slip, slap, slop" was replaced in the 1990s with a new campaign called Sunsmart that stressed the importance of seeking shade in the heat of the day.
"Between 11am and 3pm, slip under a tree. The best sunscreen of all is absolutely free." Meanwhile, melanoma rates continued to rise.
Against this background, the latest statement from the Cancer Council Australia - that some sun exposure is good for you - has provoked fevered debate among specialists.
It has been agreed by the Australian and New Zealand Bone and Mineral Society, Osteoporosis Australia and the Australasian College of Dermatologists. The cancer specialists and dermatologists are the most surprising signatories, as they are the doctors most aware of the damaging effects of the sun on the skin.
Craig Sinclair, the chairperson of the national skin cancer committee for Cancer Council Australia, says: "It's simply that, during some parts of the year, you don't need sun protection. We can now say how much exposure people need to get adequate vitamin D so they can understand that easily."
A shortage of vitamin D leads to rickets in children and osteomalacia (weak bones) in adults, contributing to the epidemic of fractures among the elderly.
Studies have also linked lack of the vitamin to the incidence of multiple sclerosis - the condition is more common in countries furthest from the equator, which get less sun - and there is evidence that it may play a role in other auto-immune diseases such as Type 1 diabetes, and in cancers of the colon, breast, prostate and ovary.
Most remarkable of all, however, was a study published in the Journal of the National Cancer Institute, which found that people with greater lifetime exposure to the sun were more likely to survive melanoma.
The researchers - the same team from the University of Sydney - say the finding is independent of increased skin awareness and earlier diagnosis, and suggest that vitamin D, melanin (the pigment that darkens the skin) and DNA repair may all be stimulated by the sun and help protect against the cancer.
The war over the sun is far from over. But those who regard it as the enemy may be in retreat. - Foreign Service