Ministers were summoned to a crisis meeting at Dorneywood, the Chancellor of the Exchequer's country retreat, a week ago to review a series of road building decisions made by Mr Strang. At first, 11 of the 12 schemes were expected to go ahead, with only the Salisbury by-pass being cancelled as a sop to environmentalists.
Following Mr Prescott's intervention, the results of which are due to be announced tomorrow, about half are expected to be either cancelled or moved back into a roads review which is part of preparations for Labour's integrated transport policy.
Mr Prescott is said to have been unimpressed with the work of Mr Strang, who is new to the transport brief.
One source said that Mr Strang had "not got a grip" or "attended to the detail" and had allowed himself to be enveloped by the civil servants of the old Department of Transport.
After the election the Department of Transport was submerged into the Department of the Environment, with Mr Prescott in overall control of the new Department of the Environment, Transport and the Regions. That gave the Deputy Prime Minister unprecedented power for an environment secretary.
A Labour MP said: "If you have people who are new to their briefs the civil servants can bounce them into feeling that they have got no alternative."
Mr Prescott's move will be seen as a victory for environmentalists and could mark the end of the dominance of the road-building lobby in Whitehall.
The old transport department had traditionally been seen as highly sympathetic to the roads lobby.
In addition to the Salisbury by-pass, the proposed widening of part of the M25 into a 12-lane motorway is likely to be scrapped tomorrow. That will create problems for Heathrow's Terminal 5 because planning application has been made on the assumption that widening proceeds.
The Birmingham Northern Relief road, which has been opposed by some Midland Labour MPs, is expected to go ahead, partly because of the compensation payments payable on cancellation.
Among candidates for the chop are the widening of the A40 into London and the Hastings bypass, part of the A25/A259 scheme. Others vulnerable include the Cumbria to Bradford road including the Bradford/ Bingley relief road.
Some MPs believe that Mr Prescott's intervention was prompted more by Treasury pressure than his commitment to greenery.
But environmentalists are optimistic that the decision could mark a turning point in transport policy and provide the first real evidence that Mr Prescott is sympathetic to their cause.Reuse content