Boris Johnson has blocked Edgware Developments plans to replace the White Lion football ground with a 189 unit development.
The Mayor has instructed Harrow Council to refuse permission to demolish the ground in Burnt Oak Broadway to make way for 189 properties.
Johnson originally supported the application but appears to have changed his mind because of the loss of open space. The land is designated as such in the council's unitary development plan.
According to the Harrow Observer, Edgware Developments may still be able to act on outline planning permision it won in September 2006 for the redevelopment of the site to provide 164 flats and 11 houses in nine blocks of three and five storey buildings.