The green and pleasant land of Britain will be virtually deserted tomorrow when the age-old battle between the countryside and the city is brought to the urban heart of Cool Britannia.

As many as 200,000 people will wind their way across London on a two-mile "March for the Countryside" to the green of Hyde Park in protest against the erosion of the country way of life.

Among this colourful band, foxhunting enthusiasts will line up with beef farmers, ramblers and Barbour-wearing "townies" who are on a crusade to save the country way of life they only experience at the weekends.

But they will also be joined by small-time farmers struggling to survive in the face of the BSE crisis; by farm workers threatened with unemployment and homelessness; and the Environment Minister, Mr Michael Meacher, who will be there to underline the government's message that it is listening to the countryside lobby.

On the surface at least, the organisers of the march, the Countryside Alliance, speak with one voice. "We are tired of an urban government telling us what to do," said one member this week, while another accused Labour of trying to "boss the countryside about". And despite its many guises, the countryside lobby says it has one aim, the protection of the country way of life from the "plastic-wrapped supermarket culture" of urban Britain.

The march itself is not about one issue, however, and that is where the government, and urban Britain, may find themselves in real difficulty. Earlier this week Labour set its face against the Country Landowners' Association with a commitment to introduce legislation extending the right to roam through open countryside.

"If voluntary means fail, we are prepared to legislate," Mr Blair said. However, the government appears to have been stung by criticism of the proposals as "the biggest erosion" of landowners' rights this century and will delay legislation for two years. Fed up with "urbanites" traipsing through their fields at the weekends, the land-owners have been joined by the Barbour brigade who want to keep the countryside for themselves and, presumably, the working class on the housing estates.

The Countryside Alliance wants the urbanites to leave the countryside alone. Urbanites want it all, it says. They want to live in quaint villages, but they certainly don't want to smell the slurry from nearby farms or see a fox shot. Added to the list of grievances is the BSE crisis, the strength of the green pound, the ban on beef on the bone and cuts in rural transport and schools. Small farmers have undoubtedly borne the brunt of the financial crisis, but it is not a new phenomenon, and consumers argue that the cost of food in the supermarkets is being kept artificially high in order to subsidise the farmers.

Added to the debate is the plight of low-paid farm workers who are being priced out of the housing market by the townies moving in.

The resentment felt by the Countryside Alliance towards the urban community has also served to polarise the debate over foxhunting. The latest polls suggest a majority of people in the countryside are opposed to fox-hunting, but the chief executive of the Countryside Alliance, Mr Robin Hanbury-Tenison, has rejected the evidence, saying it merely reflects the views of urbanites who have come to live in the countryside and imposed trendy causes on their neighbours. Blowing their trumpets in Hyde Park, the pro-hunting lobby will prepare to do battle with the "namby-pamby" city types as it did last year on the back of a private member's bill to ban hunting with dogs. However, in a concession to the pro-hunting lobby, the bill has not been given enough parliamentary time to succeed. One of the ironies of the countryside debate is the position gleefully taken up by the Tories in recent months in support of the rural community. In the 1980s the Tories agreed to a building programme whereby 300,000 acres of prime British countryside was urbanised and out-of-town supermarkets sprang up from nowhere almost every year.

Against the backdrop of a party traditionally associated with the countryside lobby, the policies appeared somewhat at odds with their voters, and critics argue that Mr William Hague's support of the countryside smacks of a party in search of a cause.

But even before the march gets under way cracks have appeared in the countryside lobby. A row has broken out between Friends of the Earth and the Countryside Alliance, which it has accused of hijacking the real issues facing the rural community.

Friends of the Earth argues that the real threat comes from the cereal barons and intensive farming by large land-owners, while the anti-foxhunting lobby says it represents the rural majority. Whatever the strength of the issues, there is no doubt that Labour faces a juggling act. The march will be a blot on Mr Blair's landscape, and the countryside is lining up to take a shot at the government.