i) births and deaths
23 April 1975: death of William Hartnell, who played the First Doctor from 1963 to 1966 and again in 1972.
ii) broadcast anniversaries
23 April 2005: broadcast of World War Three. The Doctor, Rose and Mickey defeat the Slitheen by hacking into UNIT’s computers.
23 April 2011: broadcast of The Impossible Astronaut.
The Stephenson is very long and a very long way from his best; the Cornell is very good, I’ve only read British Summertime of his and this one is much better.