Tania on the hill with bulldozers

'WE'RE squatting the entire hedge,' says James, an articulate young man in a woolly hat. 'The whole thing is hammocked up.' It is true. In between the areas where road-making has begun, in preparation for the Batheaston and Swainswick bypass on the edge of Bath, protesters have declared a whole hedge an official squat. In a hazel tree a young man is stringing hammocks from branch to branch, in preparation for a breezy night's sleep. 'Is there anything in the fighting fund?' he calls down to a red-haired young woman below - Tania de St Croix, one of the long-serving campaigners against the road.

Most of the 40 or so protesters who have gathered on Solsbury Hill since Easter are in their twenties. Some, like Tania, are only in their teens. A few have abandoned their A-levels. 'I'm typical of my age- group in that I care about the environment,' Tania says. 'When we were growing up people kept saying they wanted to save the world for the children and we were children then. We felt we'd see the end of the world and it's scary. It feels as though it's slipping away.'

A Nineties teenager, Tania is also, in contrast to the Eighties version, anti-materialist. Last August she turned down the place offered her by St Andrews University to read geography. 'Mum was disappointed,' she says. 'I think she saw me going through university and having a high-powered job, doing something important. I don't really see myself doing that. I'm not into earning lots of money.'

She says this quietly in her soft Bath accent, a slightly shy, polite teenager with an engaging giggle. Her grand name is deceptive: this is no trust-funded Sloane in rebellion against a surfeit of Colefax & Fowler. She was brought up by her mother, an accounts clerk, and went to the local comprehensive. At 12, like half her generation, she turned vegetarian. By then she and her two brothers, one now 16, the younger eight, were living with their mother in Bath, renting a bungalow that the Department of Transport had already compulsorily purchased for the planned bypass. It was the bypass that politicised young Tania.

She now shares a house in the centre of Bath, but most of the protestors are squatting in her neighbours' former homes, due for demolition. 'I love it here,' she says, 'when I come back here it feels like home.' At 12 she started to go to the meetings against the road that would despoil the hill where she played and walked her collie cross, Joseph. At 16 she joined the Green Party. By then her distrust of authority was beginning to grow. From the belief that the Establishment was imposing a wrong decision about a road to the decision not to join the Establishment is not so big a step.

Had Tania been born in 1890 she would probably, at 18, have been chaining herself to railings with Mrs Pankhurst's friends for rights for women. As it is she has been chaining herself to bulldozers to save her piece of the planet. Some of the residents of Bath would put it differently. There is a degree of resentment against the hippies on the hill. Jane Austen's city is choked with traffic and fumes, and there are many in favour of any bypass that might reduce either. Tania thinks that a better solution would be improved public transport. 'Why don't they spend the money on putting trams into Bath?' she says. 'Air pollution here breaks EC limits. My mum got asthma very recently. There were lots of children with asthma at school. There are a lot of children at the playschool I'm helping at now with asthma.'

So, last summer, when the homework and A-levels were through, Tania snubbed St Andrews and stayed in Bath, working on an environmental magazine and for the Green Party, for whom she is Bath's agent. By then the Swainswick bypass had been approved and the protest against it had collapsed. In December last year, Tania and a friend talked about whether there was still a chance to save Solsbury Hill.

Soon after, Tania went to a demonstration at the heart of green activism - Twyford Down, site of the Winchester bypass. She got talking to people and word spread around the national network of green activists and protesters that a new cause could be found in the West Country, where a road was about to slice across a hill of Arthurian legend and with an Iron Age fort. By Easter the hill was alive with figures in rainbow-coloured clothing and multiple socks, and the houses of Tania's former neighbours were full of the smell of vegan stew.

On the first day of work on the road, 14 March, Tania, so recently a schoolgirl with a passion for George Eliot and playing folk music on her recorder, found herself locked on to a digger with a bicycle chain. 'I thought - is this me?' she says. 'I'm not very brave. Then they came along with bolt cutters, so we unlocked ourselves so we could use the chains again. Mum saw me arrested on television.'

Tania de St Croix sounds a little surprised by the direction her life is taking. 'I'm learning a lot,' she says. 'About working with other people. About the system.' She is certainly working hard. There is no time for television or for boyfriends, no money for eating out. Every evening is spent planning the next day's action.

It is evening now and darkness is beginning to fall on Solsbury Hill. In the cold front room of one of the squats, 12 young people are talking intensely round a table bearing a white mouse in a cage. In the corner one of them is strumming a guitar. In the hallway, another young man is playing what seem to be Pan pipes, a haunting, seductive, other- worldly sound.