Series Number Id: GSGS 3360. [Trenches to January 1917]. "Ordnance Survey, January, 1917." Detail, grid and contours grey; German trenches and names red; British front pecked grey. Used by Major J.C. Thomson MC - OC 20th Siege Battery, 8-inch hows. Shows Brickstacks - Fosse 8. Trench map on recto: [Quarries [Hulluch Region]], 1917. Another copy: PC0528 (macrepo 71407). Location: Research Collections; Fonds: WW1 Trench Maps: France; Box number: PC21; envelope_number: 650.