Close of the Collegiate Church of St Peter

From the Wikipedia page

the Close of the Collegiate Church of St Peter was an extra-parochial area, and later civil parish, in the metropolitan area of London. It corresponded to the area of Westminster Abbey and was an enclave between the parishes of St Margaret and St John,[1] within the City and Liberty of Westminster.

In 1889 the parish became part of the County of London and in 1900 it became part of the Metropolitan Borough of Westminster.

It was abolished as a civil parish in 1922