We use store-specific data for a major UK supermarket chain to estimate the impact of planning on store output. Using the quasi-natural experiment of the variation in policies between England and other UK countries, we isolate the impact of Town Centre First policies. We find that space contributes directly to store productivity; and planning policies in England directly reduce output both by reducing store sizes and forcing stores onto less productive sites. We estimate that since the late 1980s planning policies have imposed a loss of output of at least 18.3 to 24.9% - more than a “lost decade’s” growth. JEL codes: D2, L51, L81, R32.