Superstars including George Clooney and Sir Tom Jones may take it in their stride – but there are some who would rather dye than admit to going grey.

Now researchers at Bradford University believe they have solved the sensitive problem which has baffled generations of humans after discovering the root cause of grey hair.

Working in collaboration with scientists in Mainz and Luebeck in Germany, the Bradford experts examined hair as well as cells from human hair follicles.

And they have hailed the research as a “major breakthrough” in understanding greyness, which opens up some “novel ideas” about treatment, the researchers told a scientific journal.

They are now carrying on their research, in the hope of finding a cure.

Their experiments have led to the discovery that grey hair is caused by a massive build-up of hydrogen peroxide because of wear and tear of hair follicles.

The chemical ends up blocking the normal production of melanin, the natural pigment responsible for hair, skin and eye colour – causing the hair to turn grey.

The discoveries appeared in the internationally-renowned FASEB Journal, published by the Federation of the American Societies for Experimental Biology.

Karin Schallreuter, the project’s lead researcher, said the research could also provide answers into a condition called vitiligo, which causes white patches to appear on the skin.

She said: “This discovery is a major breakthrough in the understanding of hair greying and opens up some novel ideas to combat this scenario. These are being followed up at the current time in our laboratory.”

Among the celebrities famously tackling their grey are: * Football manager Jose Mourhino became the acceptable face of greyness when he sported his distinguished look while manager of Chelsea FC.

* Hollywood beauty Jennifer Aniston revealed last month that she shed tears after finding a grey hair.

* It’s not unusual to think of Welsh superstar Sir Tom Jones with jet black hair and matching beard. But the 68-year-old singer finally revealed a new, greyer look.

The science bit

* The build-up of hydrogen peroxide in hair is caused by a reduction in an enzyme that normally breaks up the chemical into water and oxygen.

* Because of low levels of different enzymes the hair follicles cannot repair the damage caused by the chemical build up.

* The hydrogen peroxide build-up, together with the low levels of the repair enzymes, disrupted the production of another enzyme responsible for producing melanin so its production in hair follicles was very much reduced.