The government must rethink its East of England Plan after High Court ruling.

High Court judge, Mr Justice Mitting, has ruled mostly in favour of Hertfordshire County Council and the District Council of St Albans, who had banded together to attack the plan, which they claimed would add substantial levels of new housing to an already congested area that currently helps perform a vital Green Belt function around Greater London.

The judge ruled that the government must reconsider policies in the plan that earmark Hemel Hempstead, Welwyn Garden City and Hatfield for thousands of new homes.

"Inadequate consideration was given to the environmental effects of expansion," he said. 

He added that the decision had been taken to "erode the Green Belt without alternatives being considered".

However, he rejected a challenge to the allocation of 10,000 new homes on greenfield sites in north Harlow, ruling that the impact on the environment of this proposal had been adequately considered.

He said that two environmental reports had been prepared in respect of Harlow north which "adequately described the environmental impact of development".

The judge ordered the government to pay 80 per cent of Hertfordshire County Council's costs, to be assessed. He also ordered it to pay £15,000 towards St Albans' estimated legal bill of £28,000.

A DCLG spokesman said: "We are disappointed with this judgement which concerns just one part of the plan and are currently considering whether to appeal. The need for more homes has not gone away and we are determined to deliver the housing that is desperately needed in the region for families in overcrowded accommodation, on waiting lists and for first time buyers. 

"We will continue in the meantime to work with our regional partners to deliver on the vast majority of the plan and put in place much needed action in the East of England to strengthen the economy, address housing shortages and tackle climate change."