Guardian: High street retailers have been given a year to cut down on the number of plastic bags they hand out to customers or face legislation that will force them to impose a charge on every bag they give away. The chancellor said legislation could come into force in 2009 and, based on other countries’ experience, it could cut the use of plastic bags by 90%, potentially reducing the number that end up in landfill by 12 billion a year. The charge would apply to all bags, including food …