Deathline (1973) aka Raw Meat part 1 With Christopher Lee Donald Pleasence

A family of cannibals descended from Victorian railway workers, who were buried alive during construction, continue to dwell in the disused lines of the London Underground tube network. The last member of the family frequently visits the neighbouring Russell Square and Holborn stations to pick off passengers for food, then takes them back to the gruesome 'pantry' at an incomplete station. When the cannibal kidnaps and kills an important politician, he is hunted by a detective as well as an American college student and his English girlfriend who were the last to see the victim in the tube station