He was hypnotised by WOTAN in order to aid its plot to conquer Earth. While under hypnosis, he called Dodo Chaplet so that WOTAN could hypnotise her. He supervised the construction of the first War Machine in a warehouse in Covent Garden and later had Ben Jackson captured as an enemy of "mechanised evolution". When a hypnotised Polly Wright let Ben escape without sounding the alarm, he questioned her motives and had her sent back to WOTAN to be punished.
After the first War Machine was deactivated and the warehouse was raided, Green lost his memory of the recent events and was taken to the First Doctor and Sir Charles Summer. Realising he knew nothing, the Doctor had a sergeant take Green away. (TV: The War Machines)