בידספיריט | British WWI military mail in

British WWI military mail in Egypt: 25 JA 1918 stampless (OAS) civilian stationary cv ex FPO C13 (5th Mounted Bgd. attached to Austr. Mtd. Div., JERUSALEM area) to LONDON, tied by DC Proud-D4 pmk 10 months before his EKD of use w/this bgd. & 6mths before C13 recorded est. (23 July 18); officer endorsed and uncensored; slit open at top; undocumented postal period for this pmk in Proud. A discovery piece.