The Doctor in the White House, a sequence from the episode The Impossible Astronaut, series 6
[youtube=http://www.youtube.com/watch?v=Zs0qpASAtCA]
The TARDIS travels back to 8 April 1969, and ends up in the Oval Office. President Richard Nixon converses with a younger Canton Everett Delaware III about a series of phone calls he received from a young girl asking for help. The Doctor quickly gains Delaware’s trust, convincing Nixon to give him a few minutes to locate the girl.