Working alongside academics from the University of Aberdeen, the Surrey team found that women living in Scotland received 50 per cent less sunlight – a key source of vitamin D – than their counterparts in the south.

And as vitamin D deficiency can lead to greater risk of bone diseases such as osteoporosis, the research has wide-ranging implications on health care, especially in the winter.

Team member Dr Helen Macdonald said: “We cannot assume that winter requirements of vitamin D are met by the stores accumulated over summer if people do not get enough sunlight to make enough of it.

“We need to look at appropriate guidelines regarding safe sunlight exposure to strike the balance between ensuring adequate protection from the sun and obtaining vitamin D from UVB rays.”