Get some sun – prolonged gaming causes rickets?

In a recent article on Tech Radar, it was theorised in a British Medical Journal that prolonged gaming, which is almost exclusively and indoor activity apart from portable machines, is a primary factor in the rising cases of rickets over the last few years. Whereas gamers may once have chosen to run around outside kicking a soccer ball for a few hours a week, they now spend all their time indoors and become vitamin D deficient, which causes rickets. I just have to wonder, is there any sun in the UK?