Wing margin stamps come from the left and right stamps of each pane. Therefore 50% of this issue have wing margins. Be careful of stamps that have had their wing margin trimmed and then reperforated.
1862 Transatlantic mail. Very An envelope from London to Montreal, Canada 'via Londonderry' prepaid by a 6d deep lilac tied by a London E.C. '76' duplex for JU.12.1862. Montreal C.E. arrival cds on reverse for the 26th
Wing margin stamps come from the center part of the sheet. In the pane shown above the left column of stamps have wing margins, There is no such thing as a straight edge perforated stamp in GB stamps.