Who are you calling anti-social?

A 63-year-old health visitor from Hull may become the unlikeliest recipient yet of an Asbo. Her crime? Protesting against the deployment of US weaponry on British soil. Malcolm Macalister Hall meets Lindis Percy, the vicar's wife who took on a superpower

Lindis Percy is an unlikely expert on the security fencing industry and its products. She's a former midwife, after all. But up here, on a bright, windy day on the edge of the North Yorkshire Moors, she discusses the merits of "chain link" and "weld mesh".

"Weld mesh is stronger," she says. But, from her perspective, chain link is better. It's easier to climb. "You have to be very calm and, if there's barbed wire on top, not get too agitated, because then you get hooked up in it," she says. "You take your shoes off, so you can climb it with your toes. I learnt how to do it at Greenham. You have to be like a cat."

She tells me this as two armed police look on, dressed in black combat gear and carrying automatic weapons, at the main gate of RAF Menwith Hill. They know who she is. Scaling the fence, she's been in here dozens of times - and has the injunctions to prove it. She's now not allowed within 7.5 metres of the perimeter mesh, and they're watching.

And today, at Harrogate magistrates' court, she faces the extraordinary possibility of becoming probably the only wife of a Church of England priest to be served with an antisocial behaviour order (Asbo). If imposed, it will prevent her from demonstrating at the base and ban her from a huge swathe of the moors around Menwith Hill.

Run since 1966 by the US National Security Agency, Menwith Hill is reportedly the biggest communications and satellite eavesdropping post in the world. The 30 glistening white domes that encase its satellite dishes make an eerie sight on the edge of the moors a few miles from Harrogate, where curlews swoop and larks sing above the farms and dry-stone walls.

Surrounded by an opaque blanket of near-total secrecy - and some three miles of fencing topped with razor wire - the base, with its dishes and its colossal electronic systems can, reportedly, scan every international e-mail, fax and phone call made from Britain (and much of the globe) for trigger words. Until recently, the base did not even appear on Ordnance Survey maps.

Since the end of the Cold War - its raison d'être when it was set up in the Fifties - this base is alleged to have been engaged in industrial espionage, and it has played a key intelligence-gathering role in the "war on terror" and in the invasions of Afghanistan and Iraq. It is also due to play a part in America's Missile Defense System - the so-called Son of Star Wars, currently under test - which will track and destroy ballistic missiles launched against the US.

Lindis Percy has waged a relentless struggle against this and other US bases for almost 30 years. She's been arrested countless times - 30 in the past year alone - and charged with offences of obstruction, aggravated trespass and breach of bail conditions.

She regards the struggle as a lifetime's work. "I function on outrage, actually," she says with a smile. But, as an adherent of the Quaker philosophy of non-violent, peaceful protest, she insists that her tactics have always been non-threatening, even polite. "The tie-up between faith, society and politics is very dear to me," she says.

A former Greenham Common protester who now works as a health visitor in inner-city Bradford, Percy is an elegantly combative 63. She and her fellow peace campaigner Anni Rainbow founded the Campaign for the Accountability of American Bases more than a decade ago.

They stage protests every Tuesday outside the Menwith main gates, and are constantly arrested. Percy holds the Stars and Stripes - upside down - with slogans written on the flag - "Independence from America", or "Stop Star Wars". Against the might of the American and British military machines, she employs the tactics of the termite, nibbling away slowly but relentlessly. Enough chewing, for long enough, and the house, she is convinced, will fall.

As a plaintiff or defendant, she is constantly in court - defending herself on trespass charges, challenging the Ministry of Defence by opposing the rerouting of footpaths, applying for injunctions against building work, filing complaints against the North Yorkshire and MoD police who patrol the perimeter.

It has cost her a fortune, but she doesn't keep track of that. "I haven't got any money, anyway," she says. "I've been on bail since about 1986. I've had about 12 jail sentences: I served four-and-a-half months in Holloway. I've got five injunctions against me, at different American bases. I've been challenging military land by-laws since 1997. I've brought four actions against the US government and - surprise - I've lost on every one." She smiles. "But we will get there in the end."

As she gazes at the machine-gun bunkers, concrete blocks, watchtowers and razor wire by a side entrance to the base, she says she feels anger, frustration and fear. The secrecy, lack of accountability (to bodies ranging from Parliament to the local planning office), the base's warfare role, its link with nuclear weapons and its occupation by a foreign power all enrage her.

"They're so entrenched now, these bases, that they can do what they like, basically," she says. "There's an RAF commander here, but actually it's the US commander who's in charge. So it's a pretence: it's actually an American-occupied base. Since we've been involved it's just got bigger and bigger and more and more unaccountable.

"But I hold in my mind always that one day it will go - possibly not in my lifetime - but I absolutely believe that. I think that the next generation will look at our generation and think, 'Why on earth did they allow this?'"

Over cups of Earl Grey in a moorland restaurant, Percy tells how she got here. She was born into a church family, and describes herself as "well brought up". She's married to a Church of England chaplain who has spent his career preaching in workplaces and docks, and is now a Canon of York Minster in recognition of his work. She has three grown-up children and six grandchildren. In the Sixties, it was the conflict in Biafra that politicised her. It was the world's first televised famine. "I just was so affected by it. And I remember saying to my husband Christopher that we had to do something."

They raised money for Oxfam and set up two Oxfam shops, one near Wigan, another near Manchester. A qualified nurse, she trained as a midwife (and helped to care for Louise Brown, the first "test tube" baby). Then her husband's job took the family to Southampton.

"I was working as a midwife there. It was 1979, just at the time when people were starting to get worried about missiles arriving in Britain. I felt I needed to know what this was about, so Christopher and I went to a local trade-union meeting about cruise missiles coming to Greenham Common. I remember coming out thinking, 'What utter madness! What are we doing? This is about the Cold War - and it's just up the road.'"

That meeting was crucial. "I got on this road from then, really. I was a midwife, which is all about birth, and this seemed to be all about death." With a job, and a family to care for, she never lived at the Greenham camp, but travelled to the demonstrations. "I was part of the Cruisewatch group, and I was endlessly arrested at the base and on Salisbury Plain."

She takes heart from the fact that the missiles were eventually withdrawn from Greenham. "That's why what's going on now is so tragic. The missiles had gone back to the US, and it was a new millennium, and seemed to be the time to think of different ways of doing things - but look at us now, for God's sake... But I also think the Romans came, and the Romans went. The Americans came - and they will go."

She and her family moved to Hull in 1989, and she embarked on a degree in peace studies at Bradford University. It's still unfinished - protesting against the 1991 Gulf War got in the way. The family home - a church-owned semi in suburban Hull - was once searched after she was arrested under the Official Secrets Act after posing as a staff member and bluffing her way into the base in 1990. She readily concedes that her arrests, jailings and confrontations with the law have caused problems for her family.

"Over the years, inevitably, it's caused conflict," she says. "With Cruisewatch, calls would come through and you'd have to go out in the middle of the night. That causes a lot of conflict. But over the years - yes, they understand. And I think they're quite sort of proud, really," she smiles. "Christopher is brilliant, but he never comes to court because he gets so angry at the way they've behaved - the violence against me and all the rest of it."

She is outraged at the allegations made in today's Asbo application. "In nearly five years at Menwith, ours has always been a peaceful demonstration," she insists. "I don't jump around and scream at people. And we'd never use bad language. But I think the background to this is that we're the eyes and ears on the ground here, and the Americans on the base are saying, 'We don't want them here; they're causing too much trouble.'

"But we have every right to be here. This is our country, and what we've done is to challenge them." She says the base has "militarised the Dales", with its razor wire and machine guns. "It's such a scar in this beautiful countryside - and we've allowed it to happen, allowed this visiting force to take control and actually put all our security at risk. And the resources expended on it... My whole working life has been in the NHS; I'm a passionate believer in it. And we're told there aren't the resources for it. But there's never a problem finding money for these places."

She accepts that, in a heavily armed world, some surveillance may be necessary. "I can see that there has to be some intelligence-gathering, of course, because there are some really nasty people around. But I do think that it has to be accountable to someone. There have to be checks and balances. This place really abuses all systems - you get abuse of the law, abuse of democracy, abuse of the planning process - and it's not accountable.

"And here the Americans are in firm control, and they only pass a small amount of intelligence on to us. So it doesn't make sense. And all this is such out-of-date thinking, isn't it? We're in such a mess. We've got to think of different ways of doing things, instead of blowing people's brains out. It's tragic... and look at the place. It's just so offensive."

She turns her back on the base and its guns, satellite dishes and razor wire to look out over the countryside towards Nidderdale. "This land has been farmed for generations, and there are ancient rights of way across it. This is how it should look," she says, gazing out to the sunny fields and dry-stone walls.

For details of the Campaign for the Accountability of American Bases, visit www.caab.org.uk