In some cases of illicit demolition, local authorities can order the property to be rebuilt. A £6k fine seems a minimal cost of doing business for a determined developer. It looks as if an earlier planning application only involved demolishing the garage, with the rest of the work in and around the existing house. But according to the Hounslow planning portal, there's a more recent application P/2022/3149 dated October 22 (which must have been put in 9 months after the illicit demolition was actually done) that appears to require almost total demolition, except for some of the front wall, with a decision still shown as 'pending'. I wonder how the planners will react to this.
Peter Evans ● 773d