People living near the railway along the first stretch of the West Coast main line, between Euston station and Primrose Hill in north-west London, want an inquiry into the environment impact of the work, which is likely to last three years. Residents say it will lead to unbearable noise at weekends and at night. They are also worried about the threat of subsidence to their homes and contamination from asbestos, anthrax and rats.
Planning inspectors at the Department of Environment, Transport and the Regions (DETR) are considering an unusual application for planning permission, submitted by residents on behalf of Railtrack, after the company said it did not need to ask for permission because it had existing statutory rights to carry out the work.
The company and Camden council took legal opinion from leading QCs that concluded Railtrack did not need permission. But residents recruited a barrister who said Rail- track did need permission, and they applied for a ruling on whether the company could go ahead with the work - a rare device known as a "certificate of lawfulness".
The issue was referred to the DETR after the council decided it did not have enough information to make a decision. Inspectors must decide whether to grant a certificate, and if they refuse, legal experts say it will mean that Railtrack does not have planning permission and that the work must stop while the issue goes back to the council.
At this point, John Prescott as Secretary of State could call the project in for a public inquiry. A Railtrack spokeswoman said the case was so unusual the company did not know whether it would have to stop work if the decision went against it. One planning source described it as a "unique application".
Ironically, any delay to the work would be a blow to Mr Prescott in his capacity of overseeing the development of public transport, as the West Coast improvements are pivotal to improving the rail network.
Helen Bryan, a resident and former planning law barrister, said: "It seemed to me there was no point in our wringing our hands if we could identify what Railtrack did not do properly or what Camden did not do properly, and that it was more important to hammer on at the procedures rather than just get stressed in general terms."
She said she was sure a project of that size in an exclusively residential neighbourhood needed a full environmental impact assessment or a public inquiry. "Whether it is vibration, pollution or noise, the scope for adverse environmental effects is unknown and potentially unlimited."
She said that to use a planning procedure which did not involve a full environmental report was "playing Russian roulette with the potential fall-out".
Almost 16,000 people living near the railway cutting may be affected by the work. The area is a mixed community, including multi-million pound houses and large council estates. It is home to celebrities such as Oasis musicians Liam and Noel Gallagher, prominent media figures, actors and lawyers.
The campaigners insist they do not want to block the whole scheme, as they support the massive investment in public transport by Railtrack and Virgin that would allow tilting trains to run at 140mph and would increase capacity for passengers and freight.
Railtrack it had acted correctly in taking legal advice and that it was working with the local community to listen to concerns and change its plans where necessary.
A spokeswoman said: "The council has been monitoring the work for best practice and noise levels and so on. They have already been doing monitoring and have been happy with what we are doing. If the noise gets loud and we know it will disturb people we will look at measures to alleviate it using sound barriers. But in two years people will probably experience two weekends of noise." She said the company had commissioned an environmental report to look at noise, pollution and the impact on local heritage.
Tom Jeffrey, assistant director of planning at Camden, said the council was using the Control of Pollution Act to restrict noise and pollution. "We are completely confident that we have done everything correctly," he said.