Series Number Id: GSGS 2742; Sheet number: 57c NW; Edition number: 7a, Location: Research Collections; Fonds: WW1 Trench Maps: France; Box number: PC09; envelope_number: 226, Manuscript on east half of sheet: many pencil markings for advance in NE direction - battery positions, OPs etc?; Stamp on reverse: Secret. Capt. RGA. Adjt. 90 Brigade RGA.