Lot 51092 – 1916-23 10s indigo-blue in lower left corner marginal block of four mint n.h. each with variety overprint double, one albino

1916-23 10s indigo-blue in lower left corner marginal block of four mint n.h. each with variety overprint double, one albino, exceptionally fresh and well centered, a major rarity with just 60 printed and this being one of only two known blocks of 4. Ex British Postal Museum Archive with « BPMA » handstamps on reverse (S.G. £52,000+).