Description
Great Britain 1887 1s Colour standard, SG211var.
A very fine unused block of four in yellowish green overprinted "CANCELLED" type 14.
Accompanying 1987 Royal Philatelic Society certificate describes them as of "PROOF STATUS", believed to have been used for Post Office fugitive ink trials, hence the unusual colour as seen on all the 1887 colour standards.
Extremely rare.