The economic value does not mention food security, there has been a mistaken assumption that cheaply acquired redundant farm buildings within broken up farms, can be piece meal reused as industrial/commercial premises with no investment cost and maximum profit for the owner with very little consideration as to how poorly accessed and appointed units adversely affect the environment and the surrounding anob, pollution of the sites and loss of valuable grazing, eg coldharbour farm where your slack planning enforcement and stupid granting of planning applications have allowed dumped oil, paint, tyres, car parts, illegal sand blasting waste and flauted use times, make it as attractive a Brixton, and threatens local water courses and the surrounding farm land that is in the run off.