on "POSTAGE" 10c. blue block of four with sheet margin at foot, the lower left stamp showing clear retouch under "POSTAGE", fresh and fine mint. S.G. 56, £200+" /> unused Block of Four --<I> "6/cents."</I> on "POSTAGE" 10c. blue block of four with sheet margin at foot, the lower left stamp showing clear retouch under "POSTAGE", fresh and fine mint. S.G. 56, £200+ | Christie's