Ordnance Survey International

The Ordnance Survey International or Ordnance Survey Overseas Directorate its predecessors built an archive of air photography, map and survey records for the United Kingdom from 1946 to 1999. The Ordnance Survey International Collection (formerly the Ordnance Survey International Library) held mapping records that were acquired outside the UK. Although the international division opened in 1946, the OS had been involved in overseas work for almost a century (notably the 1864-65 Ordnance Survey of Jerusalem).

Source: Wikipedia — Ordnance Survey International (CC BY-SA 4.0)