A victim of modern slavery has spoken of his horrific experiences at the hands of a traveller gang who forced men to work for nothing, live in squalid conditions and beat them if they tried to escape.

Mark Ovenden was one of those kept as a slave by five members of a family who lived a luxurious life at the expense of drug addicts and alcoholics.

He was homeless when he was picked up on the streets of Bournemouth and being offered 'a job' at the Greenacres traveller site near Leighton Buzzard, Bedfordshire.

Mark Ovenden (left) told of his time as a slave group run by gang leader William Connors

He told how he was offered accommodation by the gang, who then bullied their workers in laying driveways for long hours in all weather.

Speaking on Channel 4's The Modern British Slave Trade, Mr Ovenden said: 'It would have been about eight living in a horsebox, which had wooden bunks built into the side.

'You've seen pictures of the concentration camps, the long tunnel-like barracks… and it was like that inside.'

'There was one outside cold water tap for the workers to use. Most of them hadn't showered for a couple of months at least. There was one outside toilet that didn't work.'

He added: 'It was made very clear that if I was to go out, if I tried to leave, the consequences would be pretty grave. I'd seen them punch people, kick people and threaten people's lives.'

Mr Ovenden was freed after two years with around 20 other men and his case led to William Connors and his traveller family being jailed.

Surveillance footage taken by police shows Connors bullying one of his slave at the campsite

Police told how some of the men they found at the site were missing teeth, while others had been sleeping in faeces in conditions compared to a Nazi concentration camp

The Connors owned homes with hot tubs; a fleet of cars including a Rolls-Royce and a Mercedes saloon; enjoyed Caribbean cruises and holidays in Mexico and Dubai; and had £500,000 in the bank.

But their fortune came from constructing driveways and patios using a workforce of vulnerable men kept in squalid conditions, paid a pittance, and living in fear of violence.

The workers were given alcohol and cannabis but so little food they resorted to scavenging from dustbins for leftovers.

Sian Turner, a police officer who worked on the case, told the documentary: 'You had these poor people, thin, in pitiful dress, people missing teeth with their heads down, broken men.'

Workers were made to live in caravans and a horse box owned the Connors family, who had purchased several sites

Victims said the conditions inside were like a prison camp, with beds on either side

Footage from the documentary shows the state of some of the caravans they lived in

Around 13,000 people are being held as slaves in modern Britain, working up to 115 hours a week with no pay according to the new documentary.

Anti-trafficking campaigner Megan Stewart said slavery 'is organised crime on a scale the world hasn't seen before'.

She said gangs are now targeting the homeless because it is cheaper than trafficking people in from abroad.

She said: 'The more vulnerable they are, the more likely they are to be targeted. If you don't speak English, if you look like you are an alcoholic of a drug addict, that's the sort of person the traffickers are going to be looking for. People who won't be missed.'