You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Doctor_Who

Context:
Premiering the day after the assassination of John F. Kennedy, the first episode of Doctor Who was repeated with the second episode the following week. Doctor Who has always appeared initially on the BBC's mainstream BBC One channel, where it is regarded as a family show, drawing audiences of many millions of viewers; episodes are now repeated on BBC Three. The programme's popularity has waxed and waned over the decades, with three notable periods of high ratings. The first of these was the "Dalekmania" period (circa 1964–1965), when the popularity of the Daleks regularly brought Doctor Who ratings of between 9 and 14 million, even for stories which did not feature them. The second was the late 1970s, when Tom Baker occasionally drew audiences of over 12 million.

Question:
Where have the first episodes of Doctor Who always appeared?

on the BBC's mainstream BBC One channel