Canada BCL48a

British Columbia Law Stamp 1958 Fifty cent Centennial Issue, omitted orange colour (background) in error, a very rarely seen mint block of four, natural straight edge at right, characteristic Davac dull original gum, lower pair is Never Hinged, Fine to Very Fine
(Van Dam BCL48a; catalogue value $6,750)

It has been documented that two panes of 25 were found; a third pane was used.