The heritage authority has accused planning inspector Stuart Reid of misleading the deputy prime minister in his take on Ian Ritchie's Lambeth College at Potter's Field.
A spokesperson for EH slammed Reid for 'misunderstanding' its governence procedures and his use of 'inappropriate language and tone'.
The move comes less than a week after Prescott backed Ritchie's controversial development at a development site next to Tower Bridge, ignoring EH's recommendations (AJ+ 12.10.05).
As predicted by the AJ (AJ 22.09.05), the secretary of state was 'minded to approve' the Lambeth College and coach park proposal, despite EH's concerns over its potential effect on historic views.
In his report, planning inspector Stuart Reid was highly critical of EH's approach to Ritchie's plans for a cluster of 'mini towers' on the south bank of the Thames.
Reid panned the heritage authority's officers for a lack of transparency and for failing to take on board all 'relevant considerations' when advising the London Advisory Committee - the body of experts that considers key London schemes on behalf of EH.
In an official statement, the EH spokesperson said: 'In normal circumstances we would accept the decision of the deputy prime minister, satisfied that although we might not be happy with the outcome, all the relevant material factors had been taken into account.
'However, having now read the inspector's report, we have some serious concerns at the presentation of the case he makes and are astonished that he should have denied the locus of English Heritage in key aspects. We are therefore actively considering a legal challenge.
'In actively down-playing the relevance of English Heritage's evidence, we fear he may have misled the deputy prime minister in the weight to be given to the impact of the proposed development on the historic environment.