Cover with manuscript 'Alexander F Michielsen, Post Box - 237, E.C.1, London' return address on reverse which was the undercover address for the Dutch Army in London franked with pair 1941 2½d light ultramarine GVI issue (SG 489) tied WOLVERHAMPTON STAFFS 'Post Early in the Day' machine cancel dated 19 MCH 1943 with WOLVERHAMPTON & STAFFS obliterated by a mute circular cancel in black (to disguise the origination of the communication). Addressed to 'A. Michielsen Hugens, c/o Reguma Regenund Gummimantel Fabriek. Heerbrugg (St. Gallen) Switzerland' which was the undercover address for the Dutch Army in Switzerland. Censored in the UK with 'OPENED BY EXAMINER 6596 P.C.90' censor strip at left and also in transit in Germany with Nazi censor strip on reverse. Very scarce.