7 March 1930: birth of Brian Hayles, writer of The Celestial Toymaker (First Doctor, 1966), The Smugglers (First Doctor, 1966), The Ice Warriors (Second Doctor, 1968), The Seeds of Death (Second Doctor, 1969), The Curse of Peladon (Third Doctor, 1971) and The Monster of Peladon (Third Doctor, 1974).
7 March 1934: birth of of Gordon Flemyng, director of Dr. Who and the Daleks (1965) and Daleks - Invasion Earth: 2150 A.D. (1966)
ii) broadcast and production anniversaries
7 March 1964: broadcast of "Five Hundred Eyes", third episode of the story we now call Marco Polo. Ping-Cho tells the story of Ala-eddin; Barbara is trapped in the cave of Five Hundred Eyes. (One of the lovely colour photos from the set.)
7 March 1970: broadcast of sixth episode of Doctor Who and the Silurians. The Doctor finds a cure for the Silurians' plague, but they capture him.
7 March 1981: broadcast of second episode of Logopolis. The Doctor and Adric travel to Logopolis on the instructions of the Watcher, not realising that they have brought Tegan with them and that the Master has followed them.
7 March 2005: Christopher Eccleston films his final scene.
iii) date specified in-universe:
7 March 2006: setting of World War Three (Ninth Doctor, 2005)