After the series debut in 1963 on the BBC, Doctor Who wasn't an instant sensation until the second serial introduced the Daleks. At the time, the producers and BBC executives responsible for the show couldn't have imagined it would still be going strong 60 years later. While movies often made the transition to television, it was practically unheard of for a TV show to become a feature film. However, because of the popularity of the Doctor and the Daleks, a pair of Doctor Who films starring Peter Cushing were commissioned. There was no telling in the early days how long Doctor Who would go on. In fact, the show almost ended before it even really began. The first episode, "An Unearthly Child" debuted on the BBC mere hours after the assassination of President John F. Kennedy.
Source：https://www.cbr.com/doctor-who-peter-cushing-movies-explained/
