By Stuart Richards
BBC News, Sussex
In May 2006 a police investigation at a premises in Brighton identified a Lithuanian woman who said she had been trafficked into the UK and forced to work as a prostitute.
Although ultimately nobody was prosecuted for a people trafficking-related offence in the case, the woman was placed with a support organisation in the north-east of England after she was found to have "fitted the criteria of a trafficking victim for the purposes of being housed".
It is the kind of situation which has led Sussex Police to actively dedicate more resources towards tackling the problem of sexual exploitation.
Det Sgt Jon Gross is the man who took on the task last November through a new role in the Specialist Investigations Branch.
As the UK marks the 200th anniversary of the Parliamentary Act to abolish the slave trade, he spoke to the BBC News website about police efforts to uncover and disrupt the sex slave industry, and the role of Gatwick Airport in the cross-border trade.
"Since December 2006, Sussex Police has responded to information concerning potentially exploited women working in brothels on an almost weekly basis," Det Sgt Gross said.
"We are trying to scope the scale of the problem and how best we can identify it.
"There will be victims of trafficking in every area, but the problem is that it's hidden within communities.
"Unless a force is set up to look for it, you won't necessarily find it."
Det Sgt Gross said his brief was to educate officers on how to police people trafficking into, for example, prostitution or forced labour "in the event that Sussex mounts an investigation".
He said that because victims of sexual exploitation were "the most difficult group of victims to identify", the most important thing was training people to spot the warning signs.
"They could say willingly that they are OK, but they may be afraid of the traffickers.
"But there are things to look for when you are doing a search of a premises.
"Does it look like the girls are potentially being locked in at night and held against their will? What are the amenities they've got there? All these type of things would raise the alarm."
The police's efforts are being supported by other agencies and organisations, such as the Citylight service in Brighton and Hove.
Set up by Naomi Cohen and other church volunteers in the city, the project currently offers a weekly telephone support line for sex workers.
Mrs Cohen said the ultimate aim, if a need was identified, would be to set up an outreach and accommodation service for trafficked women.
"We want to be an outside body that comes alongside the police, who the women can talk to and hopefully feel comfortable with.
"They have to go through questioning and they will be housed by the police for a few days while all this is happening.
Brighton and Hove could be a city with a hidden sex slave trade
"We will come in to wherever they are - a hostel or hotel - and check they're OK, that they've got food and clothing.
"If there are women in Sussex that have gone though this, it's an awful thing and we want to be part of helping them to recover."
Mrs Cohen said she got involved after being shocked by some of the stories around trafficking into prostitution.
"It was the abuse and deception," she said.
"Stories of families handing their daughters over, a best friend sending someone's wife to be trafficked.
"It horrifies me that this is happening in this day and age when most of us have our freedom.
"I just wanted to be a part of something that changes that and can help women to rebuild their lives."
Det Sgt Gross said: "Any group like Citylight is going to have an important role to play.
"If they are offering support visits and mentoring in the first few days [after a woman has been rescued from forced prostitution], that's fantastic for us."
Det Sgt Gross said his work also involved identifying points of entry in Sussex for traffickers bringing foreign women into the country.
"There are many routes in via road, air and rail, and any number of marinas around our coastal boundaries.
"We have Newhaven Port and Shoreham Airport, but Gatwick Airport is 'the biggie' and has implications for us and the country as a whole."
Indeed there have been several trafficking cases prosecuted in recent years where Gatwick played a major role.
'Pick up intelligence'
Three people were jailed in 2005 after two young Lithuanian women escaped from forced prostitution in Sheffield and London - they had been sold for £3,000 each during a "sex slave auction" in a coffee house at the Sussex airport.
In December last year, seven people were convicted of trafficking two eastern European women who were forced to work as prostitutes in Coventry after arriving at Gatwick.
And two more men were jailed in February after Lithuanian women were picked up from Gatwick and forced to work in the sex industry in Birmingham and Cardiff.
Three people were jailed for selling slaves in a coffee shop at Gatwick
"Gatwick needs to be a priority," Det Sgt Gross admitted.
"It would be difficult to speculate how much [trafficking] comes through there.
"We need to improve the mechanisms already in place for translating intelligence into operational activity.
"We are meeting regularly with our colleagues from Heathrow, Stansted and Dover in an effort to share best practice.
"This sort of liason really assists in the drive to identify victims and thwart the traffickers at the points of entry into the UK.
"We just need to push it forward a bit."