26 January 1973: broadcast of third episode of Invasion of the Dinosaurs. The Doctor is playing with his Tyrannosaurus; Sarah is captured by Charles grover and wakes up on a space ship three months out of Earth.
26 January 1982: broadcast of fourth episode of Four to Doomsday. This is the one with the rebounding cricket ball getting the Doctor back into the Tardis. Monarch is killed by his own virus, and Nyssa faints.
26 January 1983: broadcast of fourth episode of Snakedance. The Mara is revived; but the Doctor smashes the Great Crystal and destroys it.
26 January 1984: broadcast of first episode of Frontios. The Tardis materialises at the end of time, where Norma has a very 1984 haircut and the ground swallows people and things up - including the Tardis.
26 January 1985: broadcast of second episode of Vengeance on Varos. The Doctor evades several nasty deaths and joins forces with the Governor and the othe humans to overthrow Sil.