On October 9th, ITV broadcast an episode of its documentary Exposure, which showed Muslim clerics in British mosques prepared to marry girls aged just 14.
Among the viewers was an Irish woman in a house in Lambeth, a 57-year-old who is thought to have spent at least three decades in domestic slavery.
It is not known if she watched with the two women who shared her alleged ordeal, a 69-year-old Malaysian and a 30-year-old British national.
It is not known exactly why the documentary led her to pick up the phone and call the freephone number of Freedom Charity, a London-based charity that has worked with victims of forced marriages, or forced labour and servitude.
"Something opened up in one of the women," said Metropolitan Police detective inspector Kevin Hyland last night.
The woman, who had not been named publicly last night, told the charity she had been held captive for 30 years.
A series of telephone calls then occurred between the charity, detectives from the Metropolitan Police’s Human Trafficking Unit and the victims – a fact that indicates they were not under observation all of the time.
They had “limited freedom” from time to time, said Det Insp Hyland. Later in October, they were persuaded to leave the house. It seems this happened when the couple allegedly holding them were not there.
In the weeks after, the police, doctors and psychiatrists helped the women to slowly piece together the story of their lives over the past three decades.
For now, Det Insp Hyland is putting that as the minimum time that they were held. The youngest woman has never known freedom, but her path to Lambeth is unknown since she is not related to either victims or alleged perpetrators.
The three, said Aneeta Prem of Freedom Charity, had lived in fear, though nothing has been revealed that indicates that they were physically or sexually abused.
Detectives arrived at the south London house at 7.30am yesterday to arrest a couple in their 60s, who are not British nationals.
They were interviewed all day yesterday and days more of questioning are likely to follow, Det Insp Hyland indicated at Scotland Yard last night. London has seen cases of people being held for 10 years – and a number of cases involving Irish Travellers have seen their victims held for more than two decades – but "nothing like this", Det Insp Hyland said.
But while the three women in Lambeth may be among the longest-held slaves in Britain, they are far from being alone. Some believe the true numbers run into thousands.
Slavery is much misunderstood. It does not necessarily mean life chained in a cellar, as happened in the case in Cleveland, Ohio, where three women were freed after being held for up to a decade by Ariel Castro.
It can be about control, a control that can grow perniciously over the years until a person is no longer able to act or think freely or be able to walk out of a house simply by opening the front door and leaving.
Indeed, some of those people had been so "institutionalised" that they found it difficult to accept that they had been held against their will, or found it impossible to come to terms with life afterwards.
In some of the recent British cases, having returned to the drugs, or alcohol denied to them by the Travellers – because they wanted them fit to work – a number have since died, become homeless again, or run into other difficulties.
Meanwhile, police struggled for years to take prosecutions because slavery is so difficult to prosecute, partly because the quality of witness – vulnerable, drug-addicted or with mental problems – can be so poor.
In July last year, four members of the Bedfordshire-based Connors family – Tommy snr, his son Patrick, his daughter Josie and her husband, James John – were the first to be convicted under section 71 of the Coroners and Justice Act (2009) for forcing others into servitude.
The road into servitude and forced labour, particularly for eastern European and south Asian victims, often happens when they are recruited at home for jobs in Britain that then do not materialise, which leaves them vulnerable to exploitation.
The situation was made worse in April 2012 when the home office changed the rules for non-EU domestic workers, where a job permit was tied to one job, and one only.
Sometimes the victims face enormous debts on their arrival and are told that they have to pay them off. Sometimes, their work permit is held hostage by their employer, who forces them to clean and scrub for 18 hours at homes.