Pushing water uphill:containment policies doomed to fail

London has had a green belt for seventy years making it the ‘canary in the coal mine’ for ‘zero land take’. Because of strong demand for housing space, rising prosperity underlies rising urban land demand so rigid physical limits increase real prices over time. Agglomeration economies ensure economic growth is disproportionately focused on our biggest cites. Thus policies limiting land supply cause ever increasing problems of housing unaffordability, inequity and foregone prosperity, eventually overwhelming rigid growth boundaries. If reducing urban land take is the aim, other instruments are needed, but current justifications for zero land take need re-examination.