Croydon is the most populous London borough, with a commercial centre, its own tram network and an identity distinctly separate from central London. Customers here search for Croydon, and for the districts within it, rather than for London — which makes it far more like a self-contained town market than the borough label suggests.
Proximity is decisive, so the districts matter
As across London, Google weights distance heavily and the borough is large enough that no single location ranks across all of it. Purley, Coulsdon, Addiscombe, Thornton Heath, South Norwood, Selsdon and Shirley all search separately and have meaningfully different demographics.
South Croydon, Purley and Sanderstead in particular are considerably more affluent than the borough average, and what converts there differs from what converts in the centre.
The office economy
Croydon has one of the larger office markets outside central London, which supports a business-to-business economy — facilities services, commercial cleaning, IT support, office fit-out. Those buyers are facilities and office managers who search by capability and buy through process rather than from a map listing.
The tram changes the catchment
Croydon's tram network is unique in London, and customer catchments here follow the lines more closely than straight-line distance. A business near a stop draws from further along the route than its physical radius suggests, which is worth reflecting in the areas you claim to serve.
Do not market as central London
A Croydon business presenting itself as a London firm competes against the whole capital while giving up a strong local position in a borough of nearly four hundred thousand people. Naming Croydon, and the district within it, is almost always the better trade.