1851. 4 RBS Ferslew. Plate I, no. 38. Beautiful APRIL-COVER (SUNDAY-COVER) from Hirschholm 6.4.1851 to Frederiksborg. Very fine mute canc. This cover is from THE FIRST SUNDAY after the intruduction of postage stamps in Denmark (April 1 was a Tuesday). Only 3 covers are known and this is by far the finest. Ex. Borch Jensen. Certs. Møller BPP and Nielsen [ 1 ] [ ✉ ]