As many as two-thirds of the three million new affordable homes pledged by UK Prime Minister Gordon Brown are likely to be built on former industrial land, including former landfill sites. But at present there is no clarity over who would be held liable for the consequences of contamination created by previous owners and past use of the land, says Aon.

Bob Martin, a director of Aon's Environmental Consulting and Solutions unit, comments: “Recent case law should raise significant concerns for former owners, potential developers as well as future owners and tenants of properties built on brownfield sites. The possibility has been raised that even the current owners or tenants could be liable to meet clean up costs or other liabilities for contamination caused by former owners or redevelopers.”

A mandatory financial security requirement on past or present owners or redevelopers was dropped from the final version of the EU's Environmental Liability Directive.