"Take the B6451," said a woman. "It's near Blubberhouses."
This part of Yorkshire is shockingly beautiful and perhaps that is why Menwith Hill seems so ugly. You drive over the crest of the hill and suddenly the horizon fills up with what appear to be giant tumours. In fact they are 27 giant, golf-ball style "radomes" crowded together in what amounts to a very large field. This is a landscape freakish enough to have been photographed by Diane Arbus. Sheep graze nearby and there is a stone wall that acts as a bit of the perimeter fence.
As I drove round, a police car moved in behind me. Suddenly the walkie- talkies were buzzing. I pulled over into a lay-by to have a good look at the American flag flying in the Yorkshire breeze at the base's entrance. A military policeman walked over and started to radio in my car number plate. It seemed a rather roundabout way to get my name.
I headed out to find a by-law sign. These are troublesome things at Menwith. It may sound strange, but there is a woman who has been imprisoned for nine months because of them. Her name is Lindis Percy. She is a 57-year- old health visitor from Hull. On the face of it she hardly seems the type to end up in jail. She is even married to a vicar. But Lindis is a Quaker, and a big believer in peace.
She wants to know what is being done at Menwith Hill in our names. She believes that it is a corner of an English field that will be forever American. She wants to know if Britain has any control over this place. She is part of the Campaign for Accountability for American Bases which has caused questions to be asked in Parliament.
Lindis and the MoD are old acquaintances. Years ago, the MoD issued an injunction against her visiting the base.
In 1997, the by-laws that are posted around Menwith were ruled illegal in Yorkshire Crown Court. The MoD appealed but, in the meantime, left the signs up. Lindis asked for them to be removed. The MoD refused. Lindis then decided to put "invalid" stickers on them. The MoD took Lindis to court for civil trespass and for breaking the injunction. In March, a High Court judge sentenced her to nine months. So that is roughly how Lindis Percy became Prisoner CF9734 at HMP Highpoint in Suffolk.
Rae McGrath spent 18 years in the military, so he knows how it thinks. But he also knows how Lindis thinks, because he became a campaigner against landmines. For his work in this field, he won the Nobel Peace Prize in 1997. Mr McGrath believes that Lindis has been jailed for being a nuisance rather than a trespasser, and says she is a political prisoner. He has asked Amnesty International to declare her a prisoner of conscience. If Amnesty did, it would be a first; all previous PoCs in the UK have been to do with Northern Ireland.
"Lindis is being focused on because she is effective and committed," he says. "I mean, Quakers are a damn nuisance if they are on the other side. I would not like to get on the wrong side of a bunch of Quakers.
"She is also innovative," he says. "She's found ways of being irritating, not for the sake of it but as a way of drawing attention to the presence of Menwith Hill. It's her effectiveness that has worked. Lindis does keep turning up in their backyard, but just whose damn backyard is this?"
Menwith Hill does not seem friendly enough to be anyone's backyard. I found by-law signs at several entrances and, standing next to them, men with sub-machine-guns. I felt immediately guilty as I walked up to read one of them, and had to remind myself that the signs exist only for this very purpose.
I went to Highpoint to interview Lindis. A few days later I was told that the Prison Service was telling other journalists that I had obtained my interview through subterfuge. Indeed, they said, I had "smuggled in" my notebook. It all sounded extremely exciting. Sadly, the truth was not. I had identified myself as being from The Independent on the prison visiting order. And I had telephoned the prison to receive permission for my notebook.
The interview itself took 90 minutes. When you think about political prisoners, you tend to think about somewhere far away, say, China or Burma. You do not think Suffolk.
Lindis was having a hard time and had spent 12 nights in segregation in a cell 8ft by 11ft. There was no toilet and she had to use a chamber pot at night. She was locked up for 23 hours a day. She thinks the conditions are appalling and - in a typically Lindis move - has requested to see the Health and Safety Executive report on Highpoint.
One night in segregation was linked directly to her refusal to be strip- searched. (The Prison Service says it has the right to do this but Lindis disagrees.) The rest were imposed because Lindis was deemed to be a security risk after she had written something to her husband. What did she write?
She looks embarrassed. "It was a joke," she says.
So what was it?
"Well, you have to see it in context," she says.
"Well, I said something like: `I wish I had my rope ladder.' But it was a joke. It was a joke!"
It is the only time her voice is raised during the interview. By the time the prison authorities agreed that there was no security risk here, Lindis had been in segregation for almost two weeks. The prison service confirmed all the information Lindis had given me, though even the press officer didn't believe that they were still slopping out there until he checked.
Lindis believes in human rights the way some other people believe in football. She says that what she objects to is abuse of power. Accountability - be it from a prison officer or the Ministry of Defence - is what matters. This sounds innocuous enough. It is the kind of thing that politicians are always saying. But, really, this is what got her into prison in the first place.
Rae McGrath believes that she should not be there. "One of the reasons that countries - and they aren't all dictatorships - get away with political prisoners is that it takes a while to realise what a political prisoner is. It starts off with people like Lindis being locked up for being a nuisance. Law is dangerous because it works on precedent. Once several people have been locked up like this, it becomes the norm."