In Britain postcodes and Ordnance Survey map data at present cannot be freely used for commercial purposes-a source of loud complaints from businesses and activists.

"It's time for motorists to take a refresher in map-reading skills," said Scott Sinclair of national mapping agency Ordnance Survey.

A spokesman for Ordnance Survey said: 'map reading, whether on a paper map or digital device, is an essential skill which could save your life.