The wider urban area outside that designation includes Newport Pagnell and Woburn Sands as well as Aspley Guise (Bedfordshire) and part of Stoke Hammond civil parish.
As of June 2023[update], information about the definitions and populations of the built-up area subdivisions of the 2021 census has yet to be released.
In defining the sub-areas of the Milton Keynes urban area for the 2001 census, the ONS used the pre-designation urban and rural districts, subdividing the larger rural district by the chronological phases of urbanisation within them).
The "Walnut Tree" and "Browns Wood" sub-areas together cover the remainder of the Rural District from the Ouzel to the M1.
(The precise boundary mapping is no longer available: the information in the notes below was derived at the time.)