DI MacMillian was the Detective Inspector who witnessed the disappearance of the number 200 bus, he was also assigned to arrest Christina de Souza for robbery. He developed an attachment to the case. When the Doctor returned the number 200 bus to Earth, MacMillian also tried to arrest the Doctor for aiding Christina's escape. To which the Doctor replied "Yes, I'll just arrest myself in this police box over there", pointing to the TARDIS. (DW: Planet of the Dead)