Series Number Id: UNKNOWN. Sheet number: parts of 51b SW, SE & 57c NW, NE. Edition: 5. Trench map. "Special sheet." "Detail and trenches revised to 25-9-17" in red. "New work to 12-11-17 shown in green". "Field Survey Co., (10064)". "Approximate British Front Line 25-9-17" in black. Detail, grid and contours grey. "Printed by an Advanced Section A.P.&S.S.", WW1 Trench Map Collection: Box PC23, Envelope 718.