"It's a religious sect," he adds, politely.
"Ah, yes," I say.
"I'm afraid so," he replies.
It isn't far. Past a nursing home and some palatial private homes screened from the road by banks of flourishing rhododendrons, to the castle.
Saint Hill castle is the European headquarters of the Church of Scientology. The church or cult, or sect - depending on your point of view - is American but it has a large following both here and on the Continent. Among non- Scientologists, the group is routinely demonised. Ten years ago, a British judge described it as "immoral, socially obnoxious, corrupt, sinister, and dangerous". Two weeks ago, a jury at Lewes Crown Court acquitted a man of trying to abduct one of its members. The man said he was trying to rescue his friend, Kathleen Wilson, 23. He said she had been brainwashed and would have left if she had had any free will. The jury agreed: she had been brainwashed. The Scientologists have never suffered such a setback.
The castle is in the traditional English style, turreted, with crenellated walls. It was finished only five years ago. Walking towards the reception, you pass a bronze statue of a man holding an eternal flame and a shield. On the pedestal, there is a short epigram: "The Price of Freedom. Constant Alertness. Constant Willingness to Fight Back. There is no other price." This is attributed to L Ron Hubbard, the church's founder. The statue is dated 7 October, AD44. AD, in this context, stands for After Dianetics. Dianetics, the name coined when Hubbard published Dianetics: The Modern Science of Mental Health in 1950, and which formed the basis of his homespun "religion".
At reception, there is a young woman in uniform: blue blazer and trousers with navy-style trimmings. (Mr Hubbard was once in the American navy. Much of his church is navally themed.) The receptionist wears a badge on her chest: "What Are You Doing For the Next Billion Years?"
Soon after my arrival, Peter Mansell, the public relations officer, takes me into a conference room. We sit drinking coffee, with his colleague Margaret.
Seventeen years after coming across one of Mr Hubbard's books in a vegetable market, Mr Mansell is "clear" - which, in the language of the church, means that he is some way along the path to eternal life. But there is still a long way to go. The ultimate achievement in Mr Hubbard's church is to become an "operating thetan". Mr Mansell has not started that journey.
Mr Mansell says he recalls some of his past lives - an important precursor to eternal self-knowledge for a Scientologist.
"Yeah, I remembered a moment from the Spanish Inquisition," he says. "I was being tortured, basically. I thought I must have seen this on a movie. But by the time I had finished describing it, I knew that it was real. It was enjoyable. I was laughing all the time I was talking about it."
"But who were you?"
"I was the person accused of being heretic. You know," he says thoughtfully, "I don't remember the language they were speaking. I was describing it in English. He died in the end."
"Who died? You died?"
"I guess I was exhausted. I don't know what the autopsy was. Torture, being beaten, exhausted."
Kathleen Wilson then enters. She is quite unlike the others, much less comfortable in her uniform. She speaks with a broad accent. She was brought up in Cleveland. Was she brainwashed? "The verdict?" she says. "I was outraged. I just listened to it, cringing. It was false information. I'm not brainwashed."
Her main anger is reserved for her mother, who appeared at the trial, much to Kathleen's annoyance. She seems to have played a role in Kathleen's journey into the church. "I tried to get along with her - but everything I did she would criticise. We had this big piano. I tried to learn. All she said was: `You're doing it all wrong.' " Her father, a bricklayer, had left home when she was 11. "She used to control everything - the clothes, everything. Even my money. But everybody has to have something.
"I didn't want to argue. I told her I would move. I went when I was 19. I went with my friend, Lorna. I packed a suitcase and went to Bognor Regis. We rented a room in a house."
It was Lorna's boyfriend, Stephen, who later tried to remove her. Briefly, the three of them had shared a house. The friends eventually went their different ways and Kathleen went to Chichester, where she found work as a sales assistant in a shoe shop.
"In the shoe shop, I was doing the same thing - day in, day out," Kathleen says. "I wasn't happy with the job. I wanted to do more in life." She came across Scientology by accident. "There used to be somebody giving out leaflets on the street and I saw one of them and it said: `We only use 10 per cent of our mental potential.' They were Scientologists. I sent it off and I got the book. I then went in to the office for a personality test. There's a graph and it tells you parts you need to improve. It said I was shy.''
A year later, she moved to Saint Hill to work full time for the cult. She had finally found a place in which she seemed to fit. "They were helping people. I wanted to take the challenge on and lots of opportunities. There were chances to travel and they told me I could study art and design - which is always what I wanted to do." She pauses. "I mean I haven't actually done art and design yet, and I haven't travelled but you could do it."
Like the 250 others who work here, she receives £33 per week. Food and uniforms are free.
Kathleen is always smiling. She has shining eyes. She seems happy, if a little withdrawn when it comes to talking about herself. There is an unnerving breezy, cheery evenness about the way she talks, even about the visit from Stephen three years ago. That was the last time she saw anyone from her old life, until the trial.
"It's horrible not having your family," she says, still smiling. "I just want them to accept what I'm doing." Her mother visited the castle one Christmas. The visit was not a success. "She said she thought it was all right but she was still acting strange and wanted me to go home," Kathleen recalls.
This was the real surprise of the trial for Kathleen. After years of silence, her mother travelled unexpectedly to the courtroom to follow the proceedings. "I was shocked," Kathleen says. "I looked twice. I just wanted to talk to her. She said: `Why haven't you come home?' I kept saying you'll put me in an institution. She kept denying it."
Her mother says that when she arrived at the court, her daughter was surrounded by members of the sect. "They said she didn't dare come home because she was frightened she would be put in an institution - as if I would do such a thing to my only child. Besides, she is already in an institution, as far as I'm concerned - being brainwashed."
I am taken on a tour of the site, to the Great Hall adorned with its life-size portrait of Mr Hubbard, in a tuxedo, standing with his palm spread on a waist-high globe of the world.
On the other side of the castle are two long corridors which house the "audit" rooms - small cubicles in which Scientologists make their equivalent of confession. In each room is a small machine which looks like a video games console, except that it has a dial instead of a TV screen. This is the "e-meter". It is supposed to measure emotions. The subject holds a metal cylinder in each hand that is wired to the machine.
Hubbard borrowed the idea from the old lie detectors. Science suggests that the machine measures moisture levels on the palms - the idea being that you sweat when you lie. They say it measures tiny electrical charges generated by thoughts themselves.
After a trip around the nearby Hubbard Mansion, where the great founder lived, I ask Kathy if she will ever go home. "My mother won't accept what I'm doing," she replies. "She thinks I'm being kept prisoner. I miss her. I don't like not being able to speak to her or see her."
Then I ask how she is getting on in Scientology. She says she is a slow learner. She has been here three years and should have been some way along the route to eternal life. But she is not. Margaret says she has not yet been allowed to take part in what they call the "Purification Rundown", during which the student eats vast quantities of vitamins and spends long periods in a sauna. Margaret says it cleanses the body so that the mind can study.
"I take a little longer than the others," says Kathleen.
"What does Scientology mean for you?" I ask.
"It means knowing how to know, and you learn different things in life. There are courses for artists and business people and students. It improves different parts of your life."
"Have you remembered any of your past lives?" I ask.
"No," she says. "Not yet."