Despite numerous national appeals for information in the years following his disappearance, Gosden's reason for travelling to London that day, and his subsequent fate, have not been established.

In December 2021, detectives investigating the case arrested two men on suspicion of kidnapping and human trafficking in relation to Gosden's disappearance.

He was on the Young Gifted and Talented Programme, which was designed to enhance the educational development of the top five per cent of school pupils.

[13] During the 2006 summer holidays Gosden attended a two-week residential school at Lancaster University as part of the Young Gifted and Talented Programme.

[23] Gosden owned a couple of mobile phones between the ages of ten and twelve but he rarely used them and subsequently lost them.

[24][25](1 h 00 min 30 s) During the 2007 school summer holidays (typically July to September[26]), Gosden's parents had suggested that he travel alone to London to stay with his grandmother, but he chose not to go.

[27] At 8:05 am[28] Gosden left his house and was witnessed walking across the local park (Westfield) to his usual bus stop by family friend Rev.

[29] Instead of taking the school bus, Gosden diverted from his usual route and walked to a cash machine at a local garage[14] where he withdrew £200 from his bank account.

However, the school dialled the number of the parents either above or below Gosden in the register and the message was left on the wrong person's phone.

[39] Days after the disappearance, the family travelled to London and handed out flyers and posters in the vicinity of anywhere they felt Gosden would have had an interest in visiting, especially museums and exhibitions.

[38] The CCTV image of Gosden leaving the main concourse at King's Cross was circulated in the media accompanied by a close up of his right ear, which has a distinctive double ridge.

[13] Investigators sent the unique serial number of Gosden's PSP to Sony HQ, who found that there was no record of an account being set up or communication established on the device.

[25](43 min 30 s) A year after Gosden's disappearance, the head teacher at McAuley Catholic High School, Mary Lawrence, travelled to London with staff and pupils and distributed 15,000 leaflets.

[45] One event identified by Kevin Gosden as a possible reason for his son to have travelled to London was the 2007 YouTube gathering.

[46] Mick Neville, retired head of the Metropolitan Police's Central Images Unit, believed the SikTh theory was plausible.

[25](46 min 10 s) Finnish band HIM did a promotional signing at the HMV store on Oxford Street on Monday 17 September 2007, and performed an invitation-only show the same evening at the Borderline venue in Soho.

[25](9 min 50 s) Speaking in 2009, Kevin Gosden speculated on the reason for Andrew's disappearance: "Did he decide to do the Reginald Perrin thing,[a] and reinvent himself?

[47] Kevin Gosden claimed that the police viewed him as a suspect during the initial stages and they carried out unlawfully recorded interviews aimed at pressuring him into revealing the reason for his son's disappearance.

[8] Kevin claimed that CCTV footage from buses and the adjacent tube station was not requested by the authorities[48] and that the reported sightings of Gosden at a Pizza Hut and at Covent Garden were not followed up.

[8] There were additional unconfirmed sightings on Oxford Street on Monday 17 September,[44] and the next day, when Gosden was said to have been sleeping in a park in Southwark.

[50][44] Gosden was reportedly seen getting off a local train from Waterloo at Mortlake station on 19 September 2007 (five days after he disappeared) then possibly walking up Sheen Lane and along Upper Richmond Road.

[55] Subsequently, an individual claiming to be the man at the police station wrote anonymously to the BBC after it featured the case on The One Show.

In September 2009, the family released age-progressed images of what Gosden might look like aged sixteen, to mark the second year of his disappearance.

[58] Kevin Gosden said: "We are a pretty open family so have wondered if he was gay or struggling with his sexual identity and found it too awkward to raise.

"[58] In May 2011, the family paid a private company to conduct a sonar search of the River Thames, using the same technology that is used to locate victims and objects at sea.

[60] In 2016, Gosden's parents appealed for information on the BBC's flagship current affairs television programme Panorama.

[25](53 min 30 s) In June 2018, the Gosden family said that someone had reported an online conversation with a person with the user name 'Andy Roo' who claimed that their boyfriend had left them and they needed £200 to cover rent.

[35] On 11 January 2022, South Yorkshire Police stated that on 8 December 2021 detectives had arrested two men, aged 38 and 45, on suspicion of kidnapping and human trafficking.

[71] The following day, it was announced that numerous devices had been seized from the men for forensic investigation, which police said could take six months to a year to analyse.

[73] In January 2023, around a year after the announcement of the arrests, South Yorkshire Police said that the men remained under investigation, and that the subsequent devices were also still under examination.