Hertfordshire residents are being urged to blow the whistle on road tax cheats as part of a new initiative being run by the Driver and Vehicle Licensing Agency. The county has been chosen to pilot a new hotline scheme, which allows people to report any vehicle without a proper tax disc on public roads. The number is 0800 028 2681. Last month the DVLA estimated there were 30,000 untaxed vehicles in Hertfordshire, which were costing the £4million in lost revenue each year.