Paul and Laura Makin sat huddled together on a bench in the dusty yard at San Antonio penitentiary, casting nervous glances at the gang members casually swinging shotguns as they lean against the breeze block walls.

“Laura’s innocent. She shouldn’t be here,” Mr Makin said. “I’m pleading guilty and I will take it if I have to, but it’s more dangerous for her. She should be back with the kids.”

The Liverpool couple have spent four nights at the Venezuelan island jail after their arrest last Monday for allegedly attempting to smuggle 24kg (53lb) of cocaine to Britain.

Seized at Isla Margarita airport in front of their four children, they have been told that they face years in the prison, which is notorious for its armed clashes, prisoner deaths and a gangland culture where the inmates run the show.

Paul Makin, 31, said that he had admitted attempted trafficking, though he maintained that he thought he was transporting diamonds, not cocaine. “I’ve never had anything to do with drugs,” he claimed.

The story began, he said, back home in Liverpool when he met a friend to whom he had not spoken since his last time in prison — his second month-long sentence for minor offences. The friend, whom he did not name, said that he looked in need of a holiday, and suggested a job he could do in Margarita, a Caribbean island in Venezuelan territory that offered world-class beaches, parties and cheap package holidays.

The friend put him in touch with a young British man from East London, whom Mr Makin did not wish to name. They met on a few occasions in England and Mr Makin was told that he would travel to Margarita, be given money to buy the diamonds and return with them a couple of weeks later. The travel arrangements were made for him and suitcases supplied.

Wanting to take his two-year-old twins, Libby and Lucy, with him, he suggested to Ms Makin, from whom he had divorced recently, that she accompany him to Margarita along with her two older children, Jack, 8, and Megan, 7, from a previous relationship.

“I thought it might be a nice holiday,” Ms Makin, 31, said, emphasising that the two were no longer a couple and that she had a boyfriend back in England. “I’ve never travelled before and he has, so I let him take care of everything,” she added.

Halfway through their holiday in Margarita, the deal changed, Mr Makin said. Their British contact, who had also travelled to the island and was staying in the same hotel, rang to say that he had already collected the diamonds and would pack them for the Makins. The contact gave Mr Makin three suitcases, with the “diamonds” already stashed beneath the false bottoms. He gave Mr Makin money to have photographs of himself, Ms Makin and the four children, taken at the island’s main shopping centre, Sambil, telling him that these photographs would be handed to the National Guard at the airport.

“He told me that we would be pulled out of the line, searched briefly to make it all look real and then let go,” Mr Makin says. “Then he gave me a mobile phone which he would call once we had got through to the other side. He even showed me pictures of the guy who we were delivering to in the UK, all dripping in diamonds. He said that he supplied lots of the rappers back home, and said that I should ask him for a diamond once I got there. But I was stitched up good and proper.”

Ms Makin maintains that the first she knew of these dealings was when they were hauled into a side room at the airport and bags of white powder were pulled from the bottom of their cases, in full view of the four children.

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