Los-Nr. 422

1938, Päts 25 S., proof block of four, with printing order number of Sept.15, 1937. Register cross below pos.100. The register cross is touched by the register pin of the perforating machine and is minimally punctured. During the production of the postage stamps the imperforate archival proof sheet was probably put by mistake into the perforating machine and was removed immediately before being perforated. A rare variety showing that the archival proofs were produced together with the postage stamps. A key proof in Estonian philately, mint never hinged, fine (Hurt/Ojaste G:1, F:1)