Unpaid letter from Aalborg via Helsingør 3 April 1851 to Stockholm, with K.D.P.A. AALBORG 3/4 ANTIa-U, blue ink not recorded by Vagn Jensen after 1 april 1851, presumably blue ink used since blue ink pad's were supplied for the cancellation of the 4 RBS adhesive, blue ink only in use until 7 April 1851. Transitmark HELSINGØR 5/4 1851. Charged 36S Skilling Swedish.