The M25 has become the new city wall of London, with the Green Belt functioning as its defensive fire zone. Just beyond, or uneasily trapped within, this boundary lies a whole range of towns—places like Slough, Grays, Dartford, and Watford.

These towns are economically robust and contribute significantly to the UK economy. However, they are simultaneously socially deprived as communities. This is partly because the higher value activities they host are often utilised by people who live outside the towns or within the Green Belt, and partly because they fundamentally lack the social and public sector infrastructure of London. They sit uneasily as urban areas with inner-city demographics within essentially rural counties. (This thinking may also apply to the ex-new towns further out, such as Crawley, Basildon, and Harlow.)

Due to their location, existing land supply, and young populations, these communities provide a significant opportunity. They can deliver not only new homes at scale but also success stories in terms of economic inclusion and genuine good growth, which lifts up the existing population while increasing productivity.

These areas, which have traditionally hosted London’s key infrastructure, its reservoirs, airports, docks, etc., are generally characterised by low-density, land-heavy residential development. Despite their often good rail connectivity, they are extremely car-dominated, exhibiting all the worst characteristics of sprawling British suburbia, with the emphasis skewed toward the "sub" in terms of sense of place and community. Crucially, they represent islands of often extreme deprivation in a sea of prosperity, a dichotomy that makes their social fabric even more fragile.

The opportunity exists on the edges of these towns, which are themselves on the fringe of London, to create new, high-density communities. These developments can effectively link these towns "outside the walls" to London and utilise the amenity of what is currently degraded Green Belt; sometimes biologically rich, but generally unwelcoming and hostile.

These areas are often characterised by environmental problems, such as flooding caused by hard landscaping, interventions like the culverting of watercourses, and the use of former agricultural sites for storage and waste-linked activities.

By strategically looking at areas on the edge of London’s boundary, we can offer a solution to both the particular problems of these marginalised communities and some of London’s chronic problems, including the housing shortage and a lack of industrial space suitable for the 21st century rather than the 20th.