The London Borough of Sutton is an Outer London borough in London, England. It covers an area of 43 km2 (17 sq mi) and is the 80th largest local authority in England by population. It borders the London Borough of Croydon to the east, the London Borough of Merton to the north and the Royal Borough of Kingston upon Thames to the north-west; it also borders the Surrey boroughs of Epsom and Ewell to the west and Reigate and Banstead to the south. The local authority is Sutton London Borough Council. Its principal town is Sutton.

The London Borough of Croydon is a London borough in south London, part of Outer London. It covers an area of 87 km2 (33.6 sq mi). It is the southernmost borough of London. At its centre is the historic town of Croydon from which the borough takes its name; while other urban centres include Coulsdon, Purley, South Norwood, Norbury, New Addington, Selsdon and Thornton Heath. Croydon is mentioned in Domesday Book, and from a small market town has expanded into one of the most populous areas on the fringe of London. The borough is now one of London's leading business, financial and cultural centres, and its influence in entertainment and the arts contribute to its status as a major metropolitan centre. Its population is 390,719, making it the largest London borough and sixteenth largest English district.