Series Number Id: UNKNOWN. Sheet number: 19 NE. Secret, Army administrative situation map, coastal area. Covering British Fourth Army (Rawlinson) rear area. In right margin, "4th Field Survey Coy R E (1631)". "[4th] Field Survey Coy R.E (7521)" in red overprint in lower margin, followed by "10-9-17". Brown base map, with blue water and grid. Title portion, legend and textual note in red overprint., Location: Research Collections; Fonds: WW1 Trench Maps: France; Box number: PC27; envelope_number: 790.