Three of our biggest challenges – reaching net-zero, improving public transport and solving the housing crisis – would be better tackled if policy-makers recognised the role the built environment plays in them and were prepared to make the changes to how our cities look and function.

Before I explain why density is important I should highlight that UK cities are sparse by international standards. London, the UK's densest city, is sparser than smaller cities like Geneva or Bilbao. Its densest neighbourhood, Maida Vale, has just over 20,000 inhabitants – 30,000 less than the densest neighbourhoods in Barcelona or Paris – and other UK cities are sparser than London.