The reign of the silver fox has been long and glorious. George Clooney, Robbie Williams and even The Great British Bake Off's Paul Hollywood have capitalised on their distinguished grey barnets, oozing style and sophistication with a hair colour that lesser men have sought to change.But now the salt and pepper elite are facing competition from young pretenders who are paying to turn grey. Online retail giant Amazon has reported an 80% spike in the sale of grey hair dye.In 2013 researchers found that people who are going grey build up hydrogen peroxide in the hair follicle, which causes hair to bleach itself from the inside out. However this could be reversed by "an antioxidant" cocktail that allows "re-pigmentation" of the hair.The discovery of what makes hair grey, published in the Federation of American Societies for Experimental Biology journal, was actually made while investigating the skin disease vitiligo.The condition, which Michael Jackson claimed to suffer from, causes loss of inherited skin and hair colour...