You come against the problem here of what constitutes a town or city. For example, the actual town of Wakefield only has a population of around 77,000 but the City of Wakefield has a population of around 326,000.
Many people would consider that London boroughs don't really fit into your definition of a 'town' or a 'city', but what about Croydon? While it's actually a London borough, it's also a distinct town in its own right (with a population of about 365,000).