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. As a result, the CCW groups Welsh SSSIs using the subdivisions of Wales formed in April 1996 by the Local Government (Wales) Act 1994, resulting in 22 principal areas. Montgomery AOS lies within the county of Powys.