Originally a recurring character, Jay was considered a regular from July 2007. He was involved in a minor racism storyline, where he called another character a "black cow". EastEnders' executive producer Diederick Santer said this was inspired by the race row in Channel 4's reality show, Celebrity Big Brother, commenting: "The Celebrity Big Brother race row kicked off as I took charge of my first scripts. I thought it was fascinating because it showed there was a real need for a debate about race in Britain. [Big Brother] didn't do it particularly well, so I thought it could be something EastEnders should do. Our stuff won't be overly moralistic or preachy but it will tackle this serious issue head on."

Another controversial storyline saw Jay get involved with a gang of youths, ending with him being stabbed in the thigh. A BBC spokesperson said "This is easily one of the most shocking and controversial storylines EastEnders has ever done. It is not a decision bosses have taken lightly, but it is an issue that is top of the news agenda. [...] We're going to tread very carefully — it won't be gratuitous. The plan is to screen the episodes in the usual slots before the watershed. Hopefully by showing the suffering that gang violence can cause, some people may think twice about getting involved."

Jay is the son of Karen Brown and Jase Dyer (Stephen Lord), and grandson of Bert Atkinson (Dave Hill) and Evie Brown (Marji Campi). Karen died in 2004 of breast cancer. Jay was first mentioned on 5 December 2006, when a dying Evie told Bert that he had a grandson.

Jay first appears after Evie's funeral, when he is taken to live with Bert, per Evie's wishes. Jay steals from the local shop and the market, and is intrigued by his grandfather's criminal past. Jay tries to befriend a gang of boys who tease him when Yolande Trueman (Angela Wynter) mothers him, and tries to impress them by calling her a "black cow". Jay's father Jase then arrives in Walford, and Bert leaves Albert Square, to allow Jay and Jase to bond. Jay continues getting into trouble, becoming involved with a gang of older boys, known as the E20 crew, led by Tegs Teague (Ben Smith). Jay helps them shoplift, and they give him a knife. The gang terrorises Dot Branning (June Brown) and Jay steals her keys so the gang can break into her house. When Dot returns, the gang escape, but Jay is left hiding in the house, and he realises he has done wrong. The gang orders Jay to throw a brick through Dot's window, but he refuses and is rejected from the gang. However, Tegs later confronts Jay in a park and a violent fight breaks out, wit Jay being stabbed in the leg. Tegs is arrested, and his mother Tina (Kerry Ann White) tries to thgreaten Jay out of testifying against her son at his trial. However, she is scared off by Jase's girlfriend Dawn (Kara Tointon). Jay gives evidence at the trial and Tegs is sentenced to two years in a Young Offenders Institute.

Jay and Jase plan to flee Walford when Jase's criminal past returns in the form of his old gang. Dawn stops them leaving by setting a date for her and Jase's wedding. Jase's old gang, lead by Terry Bates (Nicholas Ball, holds Jay hostage to get revenge on Jase. Jase is able to save his son, but is killed by the gang. Jay accuses Dawn of causing his father's death and decides to go into care to get away from her. Jay is later fostered by Jase's friend Billy Mitchell (Perry Fenwick), who feels guilty for not saving Jase from the gang. Jay's behaviour worsens when he plans an arson attack against Dawn, but Billy is able to stop him, and Jay later apologises to Dawn. After staying at The Queen Victoria public house for three months, Jay moves into a flat with Billy and Janine Butcher (Charlie Brooks). Janine tries to get rid of Jay by stealing, and blaming it on Jay. When Billy believes Janine over Jay, he leaves the flat, and he meets and befriends Marissa Moore (Finn Atkins), who works at a Massage Parlour. They plan to run away together, but Marissa backs out, leaving Jay to run away alone. Upon his return, Jay lies that he is living with Bert, but is actually sleeping on a park bench. He later decides to move back in with Billy back at The Queen Victoria. Terry's trial for Jase's murder approaches and Jay learns the truth, that rather than attempting to help Jase, Billy hid to save himself. He tells Billy he hates him. Later, Billy meets Terry's wife Viv Bates (Dido Miles) who threatens to hurt Jay if Billy testifies. Jay is taken hostage as a security measure, and Billy risks his own life to save him. Billy and Jay are both rescued by the police, and Billy testifies, which results in Terry receiving life imprisonment for murder, while Billy partially redeems himself in the eyes of Jay.

In November, Billy and Jay are thrown out of The Queen Victoria, and are forced to move in with Billy's relative, Archie (Larry Lamb). When Billy is struggling with finding a job, Jay takes matters into his own hands by mugging Lucy Beale (Melissa Suffield). Jay later feels guilty, and soon him and Lucy begin to develop feelings for one another and they kiss. Jay is then later upset when Lucy is nasty to him in front of her friends. After Archie's murder, Billy and Jay are forced to move house again, this time moving in with Heather Trott (Cheryl Fergison). Several months later, while Jay is visiting Dawn, the house is repossessed, and Billy and Jay move back to The Queen Victoria.

In January 2008, the BBC received 184 complaints from viewers over 13-year-old Jay's stabbing storyline, angry that children would have seen it. Ofcom received a further seven complaints. The BBC allowed the controversial broadcast despite a clampdown on soap violence being ordered. John Beyer of Mediawatch UK said: "I think this shows that at a flagship programme such as EastEnders they are prepared to ignore public opinion, prepared to ignore the regulator and the complaints and carry on regardless." A BBC spokesperson defended the storyline, stating: "EastEnders has always tackled difficult issues and we acknowledge that some viewers could consider this storyline challenging. However, we aim to reflect real issues and during this storyline the audience will see Jay's torment through to him deciding not to yield to peer pressure like his father did many years ago. This is part of a long-running storyline that in no way glamorises the use of knives, or portrays violence in a positive light. In fact the storyline will culminate in the character of Jay doing the right thing."

Borthwick has been praised by critics for his portrayal of Jay. Nancy Banks-Smith of The Guardian wrote that the episode in which his father died "offered Jason's young son, Jay (Jamie Borthwick), a chance to steal the show, which he duly did with a touching torrent of grief. His father, a thief himself, would have been proud of him." Borthwick was nominated in the category 'Best Dramatic Performance from a Young Actor or Actress' at the 2008 British Soap Awards, and 'Best Child Actor' at the 2008 Digital Spy Soap Awards.

Present characters · Past characters · Spin-off characters · Lists of characters

Julia Smith · Tony Holland · Simon May · Mike Gibbon · Michael Ferguson · Leonard Lewis · Barbara Emile · Corinne Hollingworth · Jane Harris · Matthew Robinson · John Yorke · Louise Berridge · Kathleen Hutchison · Kate Harwood · Diederick Santer · Bryan Kirkwood