Witness protection: 'Till my husband dies, this will be our life'

"Your old life stopped and your new life has started. You live 'normal', which is normal for us, but not for anybody else."

The BBC has been given extremely rare access to someone in the closely guarded and secretive UK Protected Persons Service (UKPPS).

For more than 20 years, Sian - not her real name - says she was a victim of sustained physical and sexual domestic violence.

As a result, she and her children now live in "witness protection" conditions in a state of enforced separation and anonymity.

"When my husband dies. Until that day, we'll be doing this," she said.

Animation by Sophie Mutton