Series Number Id: UNKNOWN. Sheet number: parts of 27a NE, 27 NW, 27a SE, 27 SW. Saint-Momelin area, training area near Saint-Omer. "[4th] Field Survey Coy R.E. (8825) 16-5-18." Detail and grid grey. Manuscript in margin: 10/Royal West Kents., Location: Research Collections; Fonds: WW1 Trench Maps: France; Box number: PC15; envelope_number: 399.