proposals to overhaul the planning system look set to be scuppered in the House of Lords, after regeneration minister Lord Jeff Rooker admitted he did not know how the supply of affordable housing would be protected.
The minister's shock admission has encouraged the Lords to mount a challenge to proposals allowing developers to pay an optional tariff rather than provide affordable homes.

Baroness Sally Hamwee, the Liberal Democrat's leader on ODPM matters in the House of Lords, said: "I think there may well be rebellion, given the strength of cross-bench concern. There's appetite for a fight."

Lord Rooker's admission came in response to questioning by Joseph Rowntree Foundation director Lord Richard Best on the plan, contained in clause 46 of the Planning & Compulsory Purchase Bill now passing through the Lords.

Best highlighted concerns from the sector that the change could damage the number of affordable homes delivered: 12,000-15,000 homes a year are built through the current system.

Rooker said: "I shall ask my colleagues to find solutions that do not have unintended consequences and to give serious consideration to the suggestions that have been made." He also questioned why the government had not piloted the project before deciding to introduce it.

Robin Tetlow, director of Tetlow King Planning, said: "This is the kind of refreshing honesty we don't get in debates in the Commons. Now clause 46 must be taken out of the bill."

Gideon Amos, director of the Town & Country Planning Institute, said: "It's essential that these things are ironed out."

An ODPM spokesman said the government was still committed to the tariff idea.