Series Number Id: GSGS 2742. Sheet number: 28 NW. Edition number: 4b. "Trenches corrected to 28-1-17." "Ordnance Survey, March 1917.", Location: Research Collections; Fonds: WW1 Trench Maps: France; Box number: PC25; envelope_number: 752, Manuscript on face: blue and red crayon in Poperinghe - Elverdinghe - Valmertinghe area. Pencil-marked numbers NE of Poperinghe. Manuscript on cover: A.B.M.