Lobbying by shopworkers' union Usdaw has prompted the DTI to contact major food retail chains and ask them not to open on Christmas Day. Secretary of state Patricia Hewitt is writing to retailers and consumer and employer representatives to secure a voluntary ban. She is intervening after the latest in a line of Bills to ban Christmas Day trading from former Usdaw boss Lord Davies of Coity fell in the Commons last week due to what Usdaw condemned as "Tory wrecking tactics". Stores over 3,000 sq ft can legally open on December 25 unless it falls on a Sunday. Despite that, independent retailers had the market almost to themselves last Christmas. Only a few Somerfield stores, Sainsbury Local forecourts and Woolworths General Stores in high ethnic population areas of London opened. {{NEWS }}