Martin Bannister
Martin Bannister was an English writer living on Earth. He wrote plays and television scripts.
In a parallel universe, he was contacted by Sydney Newman to write the first script for the pilot of Doctor Who. The show never got past the pilot and Newman was fired. Martin then started writing for the police drama Juliet Bravo, and since then he concentrated his career on writing for television shows. He had a wife and a son, Philip Bannister, but he didn't care for them and cheated on his wife because he believed himself to be a great writer.
Decades later, in a nursery home, he started having dreams with his characters and settings from Doctor Who. He was contacted by Sydney Newman again to write a new script for the series, which would be brought back by the BBC 40 years after the failed pilot. He started receiving visits from his son and his grandson, whom he tried to get in touch with, without success. Martin started to have daydreams of himself as his character, Doctor Who, and believed his wardrobe to be his TARDIS. His stories got increasingly darker, with Barbara and Ian getting ultimately killed by radiation sickness, with only him and his granddaughter Susan being left alive. Ultimately, he decided to lock himself in the wardrobe and go off in travels with Susan, instead of confronting reality. In reality, Martin died of suffocation inside the wardrobe. (AUDIO: Deadline)
Personality
Bannister is a bitter, jaded person. He is shown to be extremely selfish, caring more about himself than others. He hates what’s become of his life and constantly dreams about the past when he was lauded. Though not stated, it is possible that he is going senile in his old age (or suffering from some similar condition), having difficulty remembering details of his life. He is prone to daydreaming, fantasizing about what Doctor Who would have been like if the show had been made.
In his daydreams, Bannister becomes Doctor Who, the time traveling alien who ventures through time and space. Bannister imagines Doctor Who to be a brave yet strict and cantankerous old man.
Footnotes
(https://aminoapps.com/c/doctor-who/page/item/martin-bannister/zetw_I0l2BxooLBzeGYP6EeqomPKeP)
