17th August 1990: death in a shooting accident of Graham Williams, producer of the 15th to 17th seasons of Doctor Who (the fourth to sixth Fourth Doctor seasons, from Horror of Fang Rock to Shada); also co-author of The Invasion of Time and City of Death, and author of the unbroadcast story The Nightmare Fair which brought back the Celestial Toymaker (and was released in audio format by Big Finish in 2009).
ii) broadcast anniversary
17th August 1968: broadcast of episode 2 of The Dominators. The Doctor and Jamie are examined by the Dominators; Zoe goes to the capital and tries but fails to charm the Dulcian leadership. When she and Cully return to the island, the Dominators and Quarks blow up their cave...
iii) date specified in-universe
17 and 18 August 1947 are the setting of Demons of the Punjab (Thirteenth Doctor, 2018).