 Mid and South Glamorgan were merged into a single AOS, whilst Llanelli district was included in the West Glamorgan AOS.Due to subsequent local government reorganisation in the UK since 1972, many counties and districts have been divided, merged or renamed.Using the AOS system alone would make it difficult to search for individual SSSI citations via the Countryside Council for Wales (CCW) database without knowing 1972 region divisions.