Another reason for housing sites not being developed (19 December, page 18) is restrictive covenants.
These apply mainly to infill developments, but even where planning permission has been granted, neighbours who have covenants can prevent houses being built.

If the total number of sites encumbered by covenants was assessed, a significant contribution to meeting housing targets would be found. I speak from bitter experience, having found that taking a case to the Lands Tribunal can prevent a very suitable site being developed.

Does anyone with more financial muscle than me want to buy a site?

Postscript

Rob Howard, Cambridge.