Examines HM Treasury's review of housing supply compiled by Kate Barker. The interim report has been welcomed as one of the best analyses of the dire state of the UK house building industry to date. The review suggests that both the building industry and planning policies are partly to blame for the problems associated with record low levels of house building in the UK. Housing undersupply is confirmed as a core driver of house price inflation and housing land supply is seen as the key factor affecting the number of housing completions. It characterises the house building industry as reluctant to invest in brownfield development and low in levels of innovation and considers the planning system as too complex and slow. It draws out some external constraints affecting the delivery of new housing. Looks at how the Barker review will rekindle the brownfield-greenfield debate. The Barker review is available at www.hm-treasury.gov.uk/.