Charlton Mackerel was the inventor of the Tomorrow Window.
As a child, Mackerel found people stupid. He always saw the flaws in people and aspired to be greater and not make mistakes like all who came before him.
While at university, Mackerel was given the notes to create the Tomorrow Window by his tutor, Astrabel Zar. Mackerel invented the Tomorrow Window, which showed him what his future would be according to his current state of mind. He used the Tomorrow Window to make himself rich and aspired to use it to make the lives of entire populations better by allowing them to lead a better life with a Tomorrow Window.
While on Earth unveiling the Tomorrow Windows at Tate Modern, an attempt was made on Mackerel's life by an android duplicate of Ken Livingstone that was created by Martin. Mackerel escaped with the Eighth Doctor and Fitz Kreiner.
Mackerel accompanied the Doctor to Utopia, where an auction was taking place for various alien races to buy up planets. After discovering that all the planets on sale had an identical deity, he accompanied the Doctor in search of the actor who portrayed the supposed god, Prubert Gastridge.
After finding Gastridge and discovering that he was hired to pose as a god to bring about armageddon on hundreds of worlds, Ceccecs appeared, forcing Mackerel to flee with the Doctor and Gastridge back to Utopia.
Mackerel later travelled to Minuea and discovered that Martin was the creator of the Ceccecs and was trying to kill him. Mackerel, Gastridge and the Doctor followed Martin to Gadrahadradon, where Gastridge sacrificed his life to save Mackerel from Martin. Through one of the temporal mists on the planet, Mackerel passed his notes on the invention of the Tomorrow Window to Astrabel Zar.