Not every scene was performed live; because of the increased budget — £7,552 was spent on the serial, nearly double the amount spent on "The Quatermass Experiment" — Cartier was able to include a larger proportion of pre-filmed inserts on 35 mm film, which were included during the live transmissions of each episode. Most of the pre-filmed material was shot on location at the Shell Haven oil refinery in Stanford-le-Hope, doubling for the factory where the alien creature is being grown on Earth. Filming also took place in rural Essex for material showing the meteorites being discovered in fields, and in the boiler rooms of the under-construction BBC Television Centre in London for scenes set inside the factory. The location film sequences were the most ambitious that had then been attempted in British television drama, which was usually predominantly studio-bound.