St Helier is a residential cottage estate in the London boroughs of Merton and Sutton. The portion of the estate north of Green Lane and Bishopsford Road is in Merton, the remainder is in Sutton.

The London Borough of Merton is a London borough in London, England. The borough was formed under the London Government Act 1963 in 1965 by the merger of the Municipal Borough of Mitcham, the Municipal Borough of Wimbledon and the Merton and Morden Urban District, all formerly within Surrey.