David Sowerbutts

David Sowerbutts, is a man-child from Wood Green, North London who lives with his Bontempi keyboard-playing mother Maureen Sowerbutts.

Characterization
David sowerbutts is a disturbed and twisted man. He fits the bill of an autistic savant, and has an encyclopedic knowledge of his intense obsession, serial killers and murder tactics, but is otherwise very mentally challenged and cannot deal with regular situations. He is clearly sociopathic, and has intense explosions of rage, and a somewhat perverted and deranged imagination, as his fictional murder was too disgusting for the murder club he worked at to handle, and cost him his job. He also eats food from his mother's mouth, and expressed sexual gratification when his mother tucked his pants in and did his zip up, and allowed her to scratch his back suggesting incestuous tendencies. Later, however, he gains a girlfriend, and is generally really sweet and caring towards her. He (politely) asked to fondle her breasts, albeit in public. While willing to kill to keep himself out of jail, unnecessary killing deeply upsets him.

Series 1
One night at his work as part of a murder mystery evening, David ad-libs a far more realistic and gruesome murder scenario (including disembowelment and an obscene message smeared in excrement) than the one in the script, and is fired. Upon returning home, Maureen believes her son has actually killed someone. She then finds the blackmail note saying "I know what you did", and mistakenly believes it is from Graham, David's boss.

Murder One
She decides to ask him not to go to the police, but (since Graham knew nothing about the note) he mistakenly believes Maureen is blackmailing him about his past conviction for molestation. When he tries to call the police about being blackmailed, Maureen believes he is about to give David up and so Maureen and David take him hostage and plot to murder him. Graham escapes, but gets run over as he flees.

Murder Two
Maureen decides they must kill everyone who knows about the "murder" that David committed (not realising that it wasn't real), and she and David disguise themselves as beauticians in order to kill Cheryl, another member of the company, by electrocuting her while pretending to perform electrolysis.

Murder Three
In the fourth episode, a homage to the Alfred Hitchcock film Rope, they strangle another member of the company Martin Pike. David feels guilty for accidentally killing his own father many years before; David had put an excessive amount of sleeping tablets in his father's food in an attempt to help him sleep. Before Maureen and David can leave, a man claiming to be a police inspector (Mark Gatiss) arrives at the door and, mistaking David for the house owner Martin Pike (who has just been killed) wants to interview him about a series of recent murders in the area.

While Maureen is out of the room, the "inspector" reveals that he is really an actor auditioning for a role in the murder enactments. David goes to fetch their car and Maureen, who believes the inspector knows about the murders she and David have committed, privately confesses the truth about her husband's death; she had been secretly poisoning him for months and let David take the blame when he gave him an overdose of sleeping pills. The guilt is why David was institutionalised along with the blackmailer's other victims.

The actor thinks her confession was an improvised drama scene and breaks character, revealing to her that he isn't a real inspector. He partially tells David what she had said but Maureen covers for herself with excuses. When the actor leaves, David says he doesn't want to commit any more murders, to which Maureen agrees. However, the actor returns to collect his coat and sees the real Martin Pike's body hanging up on the door where David left it. David then kills him.

Murder Four
David's next murder (of Robin) is due to take place at a wax works museum which has a section devoted to models of famous serial killers, but after luring the victim to the venue, all the wax works come to life in an elaborate musical number and convince him that the real monster is his mother, so he lets Robin go free. Maureen leaves with David, believing that he has killed Robin. Their last victim is supposed to be Lorraine, and Maureen suggests that they barbecue her corpse to "celebrate."

Episode Seven
David has a flashback to his time at Ravenhill, with a horrified Joy exclaiming that he killed Nurse Kenchington; and refuses to kill anyone else. Maureen locks him in the house and goes off to murder Lorraine by herself. She unknowingly goes to the shop where Lorraine works. Lorraine recognises her as David's mother and lets slip during the conversation that the "murder" David committed during the murder mystery evening was just an enactment. Realising the implications of what she and David have done, Maureen takes a drug overdose. She tries to smother David with a pillow, as she thinks he is asleep under a sheet, but realises too late that he has escaped and put balloons there instead. Maureen collapses. David is seen walking towards Ravenhill with what appears to be Mr Jolly's severed head in a bag.

David attempts to turn himself in by going to a Citizens' Advice Bureau, but the apathetic advisor refuses to help him. He instead goes to the grave of Nurse Kenchington. Flashbacks reveal the full story of Kenchington's murder. In the present, David hears Kenchington's voice urging him to dig up the grave, which he does. Kenchington then appears in person, seeking her locket. When she doesn't find it, she shoots David. However he is holding a watermelon (which was in the bag, David having brought it on an inexplicable whim) and it saves his life. David does not enter Ravenhill, but is close enough to hear the explosion.

Series 2
At the start of series 2, David visits Maureen, who has survived her own suicide attempt, but subsequently has developed a malignant tumour in her liver, giving her only months to live (the doctor tells David he can now save on Christmas presents). Returning home, they find another blackmail letter, once again reading "I know what you did". They immediately suspect Robin, the one person who they didn't murder, as the culprit, and confront him at an audition. Failing to get their anger across, Maureen invites Robin round for dinner the next day, who inadvertently reveals that he has a peanut allergy. At the dinner, Robin simply suffers severe indigestion and gastric reactions from the pudding laced with nuts, rather than outright death. He also tells David that he didn't send the blackmail letter. Meanwhile, Maureen gets drunk and performs an embarrassing Tina Turner act, which leads to David revealing that his mother has cancer. She lets the guests leave and goes to bed, leaving David to clear away the dinner.

Later, David meets up with the real sender of the letter - Simon, the Citizens' Advice Bureau advisor. Because he has a large amount of debt that he wants to clear, Simon asks David to murder his aunt, who is revealed to be Mr Jelly's assistant, the elderly Mrs Wren. In return, David asks a favour - to stop his mother from suffering. David breaks into Sunnydale (the home Mrs Wren lives in) and tries to kill her, but seeing what appears to be her dead body, he leaves, believing the job was already done. In reality, what he sees is another old lady named Pat, who was murdered by Detective Finney, believing her to be Mrs Wren since she had borrowed her cardigan. David returns home to find that Maureen has murdered Simon and dismembered him. However, David simply intended for him to give her a disabled parking badge to stop the "suffering" she had been having from her bad leg, not murder her.