 Tom MacRae, the writer of the episode, had previously written the two-parter "Rise of the Cybermen"/"The Age of Steel" for the second series, which featured the return of the Cybermen.As bringing back the Cybermen had limited plot opportunities and put MacRae in the "second seat" as a writer, he was pleased that he had the opportunity to do whatever he wanted.MacRae was proud of the finished script, calling it his "most accomplished piece of plotting ever".