Mark Lanchaster was a radio DJ who used the name "Ray Dio". In June 1964, he Fourth Doctor and K9 Mark II came to visit him at his pirate radio station. After the Doctor told him about the Vardans, he told him about the cancellation wave that his uncle Professor Lanchaster had given him. After this was taken by the Vardan Derek Fretus, he helped Romana II to fix her equipment to the station's equipment to stop the Vardans. (AUDIO: Wave of Destruction)

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