Police arrived to arrest her father for sexual abuse But he was making it all up

Police arrived at the family home just after 7am to arrest Mark for sexually abusing his daughter. What followed was a nightmare that would unravel two decades of trust. For the first 20 years of her life, Emily believed she had a completely normal relationship with her dad. "A good dad We were really close," she recalls.

When Fiona heard the knock at the door that morning, she had just got up. "It sounds stupid but I had just got on an exercise bike so I was in a T-shirt and pants," she explains. Looking out of the bedroom window, she saw eight people on the doorstep. "They weren't in uniform but they looked official. They had lanyards on and a dog with them."

At the top of the stairs, Fiona saw Mark already at the door. He didn't seem confused. The random stranger Mark thought he had been talking to online was in fact an undercover police officer, now standing in Fiona's living room.

The police told Emily that her father had been sharing graphic descriptions of abusing her online for years. They believed she was in immediate danger. Emily, who had recently moved out to live with friends and start her first job, was told to return home within days to meet them in person.

But Emily was certain her dad had not sexually abused her. "When she told the police that her dad had never abused her she was telling the truth. His sex fantasy chats were just that a fantasy." From that moment, her entire view of him and her childhood began to unravel.

Events like these are increasingly common. A staggering 1,000 people, nearly all men, are arrested across England and Wales every month for viewing or sharing child sexual abuse images. But Emily's story highlights growing concern about the policing of pornography and online sexual fantasies, where fantasy can destroy real families.