7 1 / 2 Heller, overprint violet, block of four from the left upper corner perfectly mint never hinged, as well the upper stamps with very weak overprint (almost blind printing), therefore the left stamp handwritten on face signed "J D M" (Lieutenant Colonel the sheepdog J. D. Mackay, governor the island and overprinter of the stamps). The block of four comes from the in the Gibbs handbook mentioned last existing original sheet, which was auctioned in Switzerland in 1984 and subsequently divided up. The sheet contained only two "J D M" signed stamps (field 1 and 3). Each stamp signed on the base Kilian, as well the original certificates Holcombe with photo of the sheet from 1983 and Kilian from 1985 enclosed. Very rare!