John Warburton was a bio-engineer for DivaDroid International.
Warburton was a talented designer of androids for the production company. He was a difficult man to get along with: pompous, ridiculous looking, mother-hen clucking, irascible and foolish. He also had a tendency to blow his top when his anger reached an uncontrollable level.
He was engaged to fellow engineer Professor Mamet but, the day before their wedding was to occur, he left her. She decided to repay his betrayal by designing her next line of mechanoids as parodies of his character flaws.
The 4000 series were programmed to be pompous and overprotective, preposterous in their appearance and getting upset over trivial problems. All their negative emotions were stored on a special piece of hardware - the Negadrive. When this drive became full, the mechanoid's head would explode in a metaphor of Warburton's temper.
The truth of their creation as part of a lover's revenge was kept from the conscienceness of the 4000 series by being stored in a protected file accessed only by a special code. The rogue simulant that owned Able was aware of the truth about Warburton and used it to subjugate him and demoralise Kryten, whose Negadrive had blown and been repaired.
Lister had to wheedle the information about Warburton from Kryten, who had realised that his creation had been part of a joke by a jilted lover. Lister pointed out that Mamet must have been sorry to lose Warburton if the size of Kryten's groinal attachment was an indicator of real life. He also made Kryten realise that he was not the droid he had been when first designed and that Mamet would barely recognise him.