1961

On 12 April 1961, Yuri Gagarin of the Soviet Union became the first human to travel into space, at least officially. (AUDIO: Thin Ice)

UNIT's predecessor, Great Britain's Intrusion Countermeasures Group, was formed. Its leader, Group Captain Ian Gilmore, began training his men. (PROSE: Who Killed Kennedy)

Peter Tracey was born. (TV: A Girl's Best Friend)

Allison Williams and Julian St. Stephen started dating. (AUDIO: Artificial Intelligence)

The Beatles gave their first show at the Cavern Club. (COMIC: What He Wants...)

Alternative timeline
In an alternative timeline in which Nazi Germany won World War II as a result of the Seventh Doctor and Ace accidentally leaving laser technology in Colditz Castle in October 1944, the Führer Adolf Hitler died at the age of 71 or 72. Prior to his death, he had stockpiled a large number of alien artefacts, including the TARDIS, but had kept them contained because he feared the implications of intelligence superior to humans. (AUDIO: Klein's Story)