SARAH JANE: I mean, well, whatever’s in that Tower, it’s got enormous powers and, well, what can we do against it?

THE DOCTOR: What I’ve always done, Sarah Jane. Improvise.

doctor who 1963
Doctor Who (1963-1989) British science fiction television series, original run (BBC)
20xS1 “The Five Doctors,” Part 2 (1983-11-23) [w. Terrance Dicks]
    (Source)

(Source (Video); dialog confirmed). This 20th Anniversary special feature was originally broadcast as a feature-length TV movie. For later releases, it was broken into four parts/episodes.