Vintage london Underground NORTHERN LINE enamel Metal Sign. More info to come.. The item “Vintage london Underground NORTHERN LINE enamel Metal Sign” is in sale since Friday, June 28, 2019. This item is in the category “Collectables\Transportation Collectables\Railwayana\Hardware Railwayana\Plates/ Signs”. The seller is “sellistrading” and is located in Rochester. This item can be shipped to United Kingdom.