||Office space in Britain is the most expensive in the world. Even in a struggling, medium sized city, like Birmingham, costs are more than 40 percent higher than in Manhattan although construction costs half as much. Taken together with research showing a significant negative net welfare effect of planning constraints in the residential sector, regulatory constraints are the obvious explanation. To investigate this we first explore the meaning of Glaeser et al’s (2005) Regulatory Tax (RT) and then estimate values for 14 British office locations. Even on the most conservative assumptions, this shows a very substantial cost of regulation in Britain - orders of magnitude greater than estimates for Manhattan condominiums. Having values going back more than 40 years allows us to investigate the political economy of the regulatory restrictions. Britain has a fiscal disincentive for communities to permit commercial development since business rates are a national tax. In all but two locations, residents control development and their main incentive to allow development is (fear of) unemployment. The useful exceptions are the City of London and Docklands, controlled by business interests, and, in the City’s case, with a unique fiscal incentive to allow development. The City is also the only office location in Britain where the RT value has fallen over time, seemingly related to an explicit loosening of planning restrictiveness in the 1980s triggered by competition from other locations. Exploiting the cross sectional panel data allows us to test these hypotheses and the results provide strong support.