You freeze. We are all grimly intimate with every detail of the West children's past; in one line, he has revealed how our knowledge will now weigh down their efforts to construct a future. Some may read in Stephen's plan an attempt to atone for his parents' crimes; inevitably others will see the appalling spectre of abused turned abuser, locked into some awful cycle.
Stephen and Mae West, the two oldest surviving children, have written a book about their childhood in Cromwell Street. It is tipped to enter the bestseller list next week. Sitting on the sofa in Mae's suburban Gloucester semi, they tussle jokily over the morning's post.
When Stephen says: "Excuse us, we're just having a little domestic," and quick as a flash, you think: "Christ! The Wests are having a domestic!", the enormity of their identity dawns. We cannot help but judge their every word or act by their parents' deeds. But should they, then, bury their history and re-invent themselves elsewhere, or salvage what they can from the past and persevere with their notoriety?
"It's weird when people say they don't get on with their family - it's who I am. Family's everything to us, and I could never let them down," says Mae, 23. Eight months' pregnant with her first child, Mae lives with a younger half-sister and her small son. Once a month, she visits her mother in Durham prison. They write most days. She has not changed her appearance, but has acquired a new name, she explains, for practical reasons.
"I couldn't get a bank account, or a loan or anything. You would fill in 25 Cromwell Street as your previous address, and they either thought it was a joke and chucked the form away, or didn't want to know." Stephen lives near by with his wife, Andrea, and their one-year-old twins; she is about to give birth to their third. Like his father, he is a local builder. Until last year he worked for Fred's old boss and drove Fred's van. When the twins were born, he reluctantly decided not to call his son Fred, but named the daughter Rose. He thinks they will probably change their surname before they start school, and talks of one day moving to Australia, but is happy for now to be Stephen West and to continue living in Gloucester.
"It's not easy," he says. "I could never get a job working for someone else, and I've tried to get a bank account three times. When we bought our house, the man who owned the estate made me fill out a questionnaire saying things like: 'Did you know your sister was murdered?'
"But I'm not ashamed. We didn't do anything wrong, so why should I leave my home? Other victims' families haven't had to move away. A lot of people would like nothing more than to see us fall to bits, and I won't."
It is our understanding that abuse can often be cyclical which places the pair in such a curious position - at once both objects of our sympathy, and our suspicion.
"Social services visit our house morning and night, seven days a week, and they've threatened to take the kids off me," Stephen says. "The police told me: 'Face it, you're abused and you're an abuser.' But before the twins were even born, I'd made a decision to break the cycle." He sees a psychotherapist regularly, but feels others will have a wary eye on him all his life.
Candid but eerie is his admission that he sometimes doubts himself. "I've sat down and thought, Jesus Christ, what if it entered my mind one day to hurt someone? I know I'm so much like my dad in his nature. Not his bad nature, mind, but certain things. Sometimes I say something and it's like he said it. Then I get worried."
In the book, Mae recounts incidents where Stephen beat his wife. The couple had been together only three months when Fred West was arrested, and the relationship has been volatile at times.
Mae is no longer with the father of her baby. She says: "I don't really trust anyone any more. A lot of men won't ever want to know me now, and there are others who just want to go out with you so they can say they've been with Mae West."
In many ways she betrays little sign of their background. Her home is a model of suburban convention, with pastel borders and faux mahogany sideboard, unrecognisable from the anarchic eccentricities of 25 Cromwell Street. She is accustomed to stares and whispers, and can be wearily knowing: "When I say something like, 'Oh, my mum taught me that', I can see people thinking - 'God, what else did she teach you?' " She is also curiously oblivious to the awful black humour which overlays so much of what she says. "He was a brilliant dad, really," she says at one point. "Well, apart from he wouldn't leave you alone. But you could have a good old laugh with him. You would never think he was a murderer." Of Rose she says: "She's more like a normal mum, now. Which is a shame, because she's locked up." It's such a pity, she says, that her mother's five grandchildren will all grow up with their gran in prison inside, because Rose liked children so much.
Stephen claims in the book that his childhood "hasn't left any scars", but he is a more obviously troubled character. Strangely dandy for nine in the morning, and rather proudly nursing a hangover, at times he gives the impression of relishing his macabre notoriety. Girls, apparently, have been calling Mae to tell them how much they fancy him, which pleases him.
But his anger is evident, and sits oddly alongside the echoes of psychospeak which stray into conversation. "I have got a short temper. Partly, that's due to the very intense pressure I've been placed under," he explains. "And partly it's just because, well, I've got a short temper," he finishes up. Like Mae, his deadpan delivery can be horribly, unintentionally funny.
"I think about the other victims' families a lot. We know what it's like to lose somebody through this. Obviously we've got the added burden of it being our dad who did it."
Neither anticipates Christmas with any great pleasure. Stephen will spend it with his wife and her family. Mae says: "We don't think we'll really bother too much with it. We'll just have a quiet day in." She has already had her December visit, so cannot see Rose. They don't plan to mark the anniversary, on New Year's Day, of their father's suicide.
As we get up to leave, we mention that we're going to Cromwell Street. Stephen frowns, and warns: "They're not altogether there, down there. Actually, they're all nutters down there. Definitely got a screw loose."