By the time you finish reading this article, at least three children will have gone missing in the UK. The Missing People charity, founded in 1986 in the wake of the still unsolved Suzy Lamplugh case, believe that a child goes missing in the UK every three minutes. The charity report that around 306,000 children in the UK go missing every year.

In 2007, as a photograph of a three-year-old girl called Madeleine was shared across the world, you might have been forgiven for thinking there was just one British child to have disappeared that year. However, also in 2007, a few months after Madeleine McCann seemingly vanished, a 14-year-old boy named Andrew Gosden exited King's Cross Station into oblivion. Much like Madeleine's photo showed her to have the rare eye defect coloboma, Andrew had a unique physical trait too, a double ridge on his right ear.

Friday the 14th of September, 2007. The last day Kevin Gosden would ever see his son.

"The night before Andrew went missing," says Kevin, "we lay on the floor and did a jigsaw. It was an entirely unremarkable evening. We played games and did arts and crafts stuff with the kids a lot, ever since they were little. It's just what we did that night…"

Kevin struggles to find the words. This year, his and his family's nightmare will be 11 years long.

"Never did I think…"

The missing person poster for Andrew Gosden, via Help Us to Find Andrew

Andrew Gosden was born on the 10th of July, 1993. He lived in Balby, Doncaster, a suburb of the South Yorkshire town that is largely unremarkable, save for the fact the classic BBC sitcom Open All Hours was once filmed there. Andrew was smart. He was a member of the Young Gifted and Talented programme, a scheme designed to enhance the educational development of the top 5 percent of schoolchildren. Teachers at McAuley Catholic High School believed he was a shoe-in for Cambridge.

"Andrew was too clever by half," remembers Kevin. "He tended to say little about school, but we remember him coming back from summer school for gifted and talented kids, and he was absolutely enthused about what he had been doing. To be honest, I think Andrew saw school as something you sort of had to do just in order to have choices open to you for adult life."

Andrew had friends, but he didn't socialise with them all that much outside of school. Nothing suggests he was bullied. There was no evidence of depression. He liked his own company. He loved video games. He never left the house without leaving a note. Kevin says he was especially close to his sister, Charlotte, two years his senior. They both shared an interest in the sort of bands you'd see on the cover of Kerrang! magazine.

In fact, the day Andrew went missing, he was wearing a Slipknot T-shirt. Family photos that have emerged in the years since his disappearance have seen him sporting T-shirts bearing the logos of Funeral for a Friend, Cradle of Filth and HIM. Posters of these bands used to hang his bedroom walls, though they’ve long been taken away by police to swab for fingerprints.

There's a popular theory on Reddit, that Andrew got on the train that morning, from Doncaster to London King's Cross, to attend a concert. 30 Seconds to Mars were playing in town that evening. HIM were doing an in-store at an HMV, which was then on Oxford Street, three days later. Then SiKTh were playing a rescheduled show at the Carling Academy in Islington, which would – until their reunion in 2014 – be the last to feature singer Mikee Goodman. Mick Neville, retired head of the Metropolitan Police's Central Images Unit, has stated the "SiKTh theory" is plausible.

But then there’s been a lot of theories.

Andrew Gosden as a child

Here's what is known about Andrew's disappearance. On the last day his family saw him, Andrew woke late. He seemed irritable. His family say this was out of character. He left the house at 8.05AM. Then, instead of catching the bus to school, he went to sit in Westfield Park, on nearby Littlemoor Lane. Then, at a time he knew the rest of his family would have left the house for the day, he returned home. He was captured on the closed-circuit recording system of his neighbour.

Andrew went to his room, took off his uniform and put it in the washing machine. He hung his blazer on the back of a chair, changed into his regular clothes, picked up his wallet, keys and PSP console (though not the charger) and put them into the type of cloth satchel – covered in patches of bands, obviously – eternally beloved by young rock fans. He left the house at 8.30AM and began to walk in the direction of Doncaster Railway Station.

En-route, he stopped at an ATM and drew out £200 of the £214 in his account. This is the last time his account has seen a withdrawal since that day, though in the years since his disappearance his parents continue to top it up. Strangely, he'd left £100 of birthday money in his bedroom back in Balby. At the station, he bought a one-way ticket to London, despite the clerk informing him that, for less than a pound extra, he could get a return. He got the train at 9.35AM. He got off at 11.20AM. He was captured on King's Cross CCTV at 11.25AM. Though there was a sighting of a boy who looked like Andrew in Pizza Hut on Oxford Street later that day – one his parents believe is credible – this would be the last confirmed sighting of Andrew Gosden.

If you’re wondering why more CCTV footage of Andrew in one of the world's most surveilled cities doesn't exist , so was Kevin, until he learned the police hadn't reviewed the King's Cross footage until a month after Andrew's disappearance. Nobody had ever requested footage from the tube station nearby. By the time anyone did, the trail was cold. Just two examples of mistakes within an investigation which is littered with police errors and terrible luck.

Andrew didn’t have a mobile phone ("He had a couple aged ten to 12," says Kevin. "He managed to lose them, never used them much to begin with, and our offers to replace them were met with, "Can I have an Xbox instead?"). The house had one computer, a laptop, a birthday present for Charlotte, but she'd only had it for eight weeks prior to Andrew's disappearance. Kevin says Andrew didn’t have an email address. The police took the computers from Andrew's school and from Doncaster Library – they found nothing. Sony confirmed he didn't have an online account on his PSP. He had no social media; "he just didn’t seem very social", Charlotte told the Thin Air podcast last year.

Though his parents are religious, Andrew stopped going to church 18 months before his appearance. He was a Cub Scout, though stopped attending a few months prior to the 14th of September. That summer, his parents had suggested he stay with his grandmother in London, but he didn’t want to go. "Andrew was-slash-is very deep," says his father. "He was the sort of person who would listen a great deal but not say much. When he did say something, it was generally worth listening to. He'd obviously thought about it a great deal from several different angles before reaching his conclusion…

"I think he was partly following Charlotte in stopping church," continues Kevin. "We always made a point of saying to them that it was their choice whether they wanted to go to church. With Scouts, he just said he was bored. He seemed to be going through a quiet phase, which we assumed would alter in due course. We got the impression he couldn't be bothered to get himself organised on taking up the offer to go to his grandmother’s. Which didn't seem that odd at 14..."

Projections of what Andrew might look like today.

Some more theories: he's in the Thames. In May of 2011, a company specialising in at-sea-rescue, offered to perform a sonar search of the capital's river. It resulted in the discovery of a body, though it wasn't Andrew's. The aforementioned Mick Neville believes the possibilities of a connection between Andrew and Alex Sloley, a 16-year-old who went missing from London ten months after him, should be investigated.

Or maybe he’s in Shrewsbury.

In November of 2008, a man visited Leominster Police Station out of hours, professing, via intercom, to have information about Andrew. By the time someone had come to take his information, the man had disappeared. After the BBC featured the Andrew Gosden case on The One Show, the BBC received an anonymous letter from someone claiming to be the man from Leominster Police Station. It claimed that Andrew had been sighted in Shrewsbury. There is no confirmation the person who wrote the letter and the man at the police station are one and the same.

There have also been "sightings" in Plymouth, South Wales, Southend and Birkenhead, though recently all efforts have looked to Lincoln for answers.

"Last year, around the time of the tenth anniversary of Andrew’s disappearance, we received a tip from someone who said he’d been talking to someone named 'Andyroo' online," says Kevin. "The person our contact was talking to said, 'My partner has just walked out and I need help.' Our contact offered to help, asked 'Andyroo' what he needed. 'Andyroo' told him he needed £200 to make rent. Our contact noticed 'Andyroo' was listed as living in Lincoln, some distance from him, and so offered to transfer some money to help him out. 'Andyroo' said he didn't have a bank account because he'd left home when he was 14. He said he'd 'just felt like it'. What's really interesting about this, is that our nickname for Andrew as a kid was 'Roo'… "The police made enquiries with the web admins," continues Kevin. "They asked us to keep it quiet while they did so. Unfortunately, the website had recently changed its systems and lost a lot of data, so they couldn’t give us any user data. Since then, we’ve been driving around Lincoln looking for someone who looks like Andrew, but nothing has come of it…"