18 May 1928: birth of John Abineri, who played van Lutyens in Fury from the Deep (Second Doctor, 1967), Carrington in The Ambassadors of Death (Third Doctor, 1970), Railton in Death to the Daleks (Third Doctor, 1974) and Ranquin in The Power of Kroll (Fourth Doctor, 1978-79)
ii) broadcast anniversaries
18 May 1968: broadcast of fourth episode of The Wheel in Space. The Cybermen emerge and start to take over the Wheel.
18 May 1974: broadcast of third epsiode of Planet of the Spiders. While exploring the meditation centre, Sarah is transported to Metebelis Three, and the Doctor follows her in the Tardis.
18 May 2013: webcast of Strax Field Report: A Glorious Day.
Also 18 May 2013: broadcast of The Name of the Doctor. ending the regular stories of Series 7 of New Who. The Doctor is summoned to Trenzalore where it was said he would fall. But what does the alleged site of his final battle have to do with the mystery of Clara Oswald? Can the Paternoster Gang help him avoid his apparent destiny? And who's John Hurt playing?
iii) date specified in canon
18 May 1969: setting of much of Paul Leonard's 1999 Eighth Doctor novel, Resurrection Man.