London, England - Sofia Allam simply could not believe it. Her kind, loving father was sitting in front of her threatening to kill her. He said she had brought shame and humiliation on him, that she was now "worse than the muck on their shoes" and she deserved to die.
Religious persecution of the kind Sofia suffers is increasingly common in Britain today
And what had brought on his transformation? He had discovered that she had left the Muslim faith in which he had raised her and become a Christian.
"He said he couldn't have me in the house now that I was a Kaffir [an insulting term for a non-Muslim]," Sofia - not her real name - remembers.
"He said I was damned for ever. He insulted me horribly. I couldn't recognise that man as the father who had been so kind to me as I was growing up.
"My mother's transformation was even worse. She constantly beat me about the head. She screamed at me all the time. I remember saying to them, as they were shouting death threats, 'Mum, Dad - you're saying you should kill me… but I'm your daughter! Don't you realise that?'?"
They did not: they insisted they wanted her out of their house.
After three weeks of bullying, and just before her parents physically threw her out, Sofia left. "They put their loyalty to Islam above any love for me," she says, her voice faltering slightly.
"It was such a shock. I remember thinking when they brought all my uncles round to try to intimidate me - all these men were lined up telling me how terrible a person I was, how the devil had taken me - I remember thinking, how can this be happening? Because this isn't Lahore in Pakistan. This is Dagenham in London! This is Britain!"
Religious persecution of the kind Sofia suffers, however, is increasingly common in Britain today. It is hard to get an accurate notion of the scale of the problem, not least because very few of the people who leave Islam are willing to complain to the police about the way they are treated.
"Intimidation is very widespread and pretty effective," says Maryam Namazie, a spokesperson for the Council of Ex-Muslims of Britain. She believes that many of the deaths classified as "honour killings" are actually murders of people who have renounced Islam.
"I get threatened all the time: emails, letters, phone calls," she says. "When I returned home this afternoon, for example, there was a death threat waiting for me on my answering machine…" She laughs nervously.
"A lot of them aren't serious, but occasionally they are. I went to the police about one set of threats. They took a statement from me but that was it - they never contacted me again."
That treatment is in sharp contrast to the seriousness with which the Dutch and German police responded when members of the Council of Ex-Muslims in those countries made complaints to the police about death threats.
"The heads of the Dutch and German organisations are today both living under police protection," Ms Namazie explains.
Last week, it was reported that the daughter of a British imam was living under police protection, after receiving death threats from her family for having left Islam.
But it is not only extreme Muslim families that believe it is their religious duty to threaten, and even kill, members who renounce the religion.
"My father could not be described as an extremist," insists Sofia, who is now 31. "We read the Koran and prayed regularly together, but he never insisted on my wearing Islamic dress and he was quite happy that I went to the local comprehensive, which was all girls, but not by any means dominated by Muslims."
There were conflicts when Sofia's parents tried to arrange a marriage for her at the age of 18, but they seemed to accept her decision to continue her education.
"They even let me go away to university," she explains. "I appreciated how difficult it was for them to grant me that freedom, and I was very grateful for it. In the event, though, I only lasted three months - I just got so homesick that I had to come back to Mum and Dad."
Sofia got a job in a hotel and quickly became a manager. Her interest in Christianity was entirely self-generated. She acquired a Bible, which she hid in her bedroom. But four years ago, her mother found it.
"She confronted me one morning with, 'Are you still a Muslim?' I had to tell the truth: I didn't think I was. From that moment on, she basically disowned me. My father was shocked and saddened. But the reality was that my parents behaved to me as if they thought it would be much better if I was dead."
Most leading Muslims in Britain are unequivocal in their denunciation of British Muslim parents who threaten to kill their children for leaving Islam.
Ibrahim Mogra, of the Muslim Council of Britain (MCB), says that it is "absolutely disgraceful behaviour… In Britain, no Muslim has the right to harm one hair of someone who decides to leave Islam."
Inayat Bunglawala, also a spokesman for the MCB, insists that such behaviour in Britain is "awful and quite wrong. The police should crack down on it."
And yet a significant portion of British Muslims think that such behaviour is not merely right, but a religious obligation: a survey by the think-tank Policy Exchange, for instance, revealed that 36 per cent of young Muslims believe that those who leave Islam should be killed.
There is considerable support, from the Koran and other sacred Islamic texts, for that position - which may explain why, out of the 57 Islamic states in the world today, seven have a legal code that punishes Muslims who leave the religion with death.
That number may soon increase: Pakistan is currently considering a Bill that would make apostasy a capital crime for men and one carrying a sentence of imprisonment for women.
As it is, ordinary Pakistanis take the law into their own hands and kill Muslim apostates. The same thing happens in Turkey where, earlier this year, two people were killed for "having turned away from Islam".
Patrick Sookhdeo was born a Muslim, but later converted to Christianity. He is now international director of the Barnabas Fund, an organisation that aims to research and to ameliorate the conditions of Christians living in countries hostile to their religion.
He notes that "all four schools of Sunni law, as well as the Shia variety, call for the death penalty for apostates. Most Muslim scholars say that Muslim religious law - sharia - requires the death penalty for apostasy.
"In 2004, Prince Charles called a meeting of leading Muslims to discuss the issue," adds Dr Sookhdeo. "I was there. All the Muslim leaders at that meeting agreed that the penalty in sharia is death. The hope was that they would issue a public declaration repudiating that doctrine, but not one of them did."
The reluctance to condemn sharia law is widespread. I asked Mr Bunglawala, for instance, to condemn the Islamic states that imposed the death penalty for apostasy. He did not do so, merely commenting that "it was a matter for those states".
Given the acceptance by some that Muslim religious law does indeed require that apostates be killed, it is hardly surprising that many ordinary Muslims think that it is their religious duty to carry out that punishment - or at least to threaten it.
"There can't be freedom of religion in Britain while so many British Muslims take that attitude," Sofia says. "It frightens me, because attitudes have hardened over the past decade."
Still, won't her parents eventually just recognise that she has chosen to change her religion? Won't they, in 10 years' time, accept her back? "No," Sofia says, her eyes full of tears. "That will never happen. I know it. They will never accept me the way I am."