Previously unknown error stamps auctioned for $16,900LONDON – An stamp error has been discovered by auctioneers at Stanley Gibbons. A sheet of 20 1982 British Motor Cars 19 1/2 pence featuring a previously unrecorded ‘double gray’ printing error sold for £10,925 ($16,900). The sheet of 20, which has 12 examples affected by the double printing error, was described as “a stunning […]