VARIETY 1991 HAMSTREET ERROR of VALUE 26p for 28p Superb Unmounted Mint sg1579va. Only a handful of these well-known varieties exist. Comes with ordinary issued 28p for comparison. See three scans front & back. The item "VARIETY 1991 HAMSTREET ERROR of VALUE 26p for 28p Superb Unmounted Mint sg1579va" is in sale since Monday, August 26, 2019.This item is in the category "Stamps\Great Britain\Elizabeth II\Decimal (1971-Now)". The seller is "aper9940" and is located in Harlow. This item can be shipped to United Kingdom.