Radio Five Live interview about the dangers

Scientists in Bradford have subjected the famous strip to a series of tests in the laboratory and say the material is too thin.

The researchers are particularly worried because some of England's matches will be played under the intense rays of the Mediterranean sun - England's first game against Tunisia is in Marseilles.

Protection factor

The warnings apply just as much to fans

Writing in the Lancet, Dr Andrew Wright and a group of experts from hospitals in Bradford and London say the players should apply a sun cream during games.

The Bradford group shone ultraviolet rays through one layer of a child's replica T-shirt to test how much radiation gets through to the skin. Using a scale comparable to the protection factors used to rate sun creams, they were able to measure the performance of the England kit.

They found the material to be wanting: it gave no more protection than a factor 10 cream. This looks poor against many other modern fabrics: in Australia, for example, the minimum standard for clothing has been set at factor 20.

Fans and stars alike

Although it was only a replica T-shirt that was tested, the material was identical to that used in adult shirts, including those worn by the England team.

As such, Dr Wright says the warnings apply equally to the fans. He is concerned about supporters who travel to France without tickets and end up sitting outside World Cup stadia watching games on large screens, wearing nothing but their replica shirts.

"It should also be noted that the presence of water, either from atmospheric humidity or perspiration, would reduce the ultraviolet protection factor.

"My advice to the players is to put some sunblock on underneath their shirts.

"The last thing I'd want is for England not to win the World Cup because the team got sunburned during training or whatever."