April Fools' Day

April Fools' Day was a holiday celebrated on 1 April. On this day it was customary for people to play practical jokes and hoaxes on one another.

On 1 April 1963, Ian Chesterton sent one of his Coal Hill School students, Little Titch Critchley, to the supplies cupboard for "a left-handed blackboard rubber". Later that morning, Ian started a snowball fight with Mr Okehurst, shouting, "April fool!" That afternoon, when John Brent tried to tell his father about the snowmen which had been animated by the Cold, Captain Brent thought his son was playing an April Fools' joke. (PROSE: Time and Relative)

When Harold sent a distress call warning Deimos Moonbase about a group of Ice Warriors taking over the tourist shuttle, Gregson Grenville responded, "Yeah, yeah. Very funny, Luigi. Happy April Fools to you too." (AUDIO: Deimos)

April Fools' jokes in the real world

 * An issue of the Doctor Who fanzine Dream Watch Bulletin said there was a sixth episode of The Dæmons planned which would feature escaping UNIT.
 * In issue 76 of Doctor Who Magazine, there was a feature about rushes for an abandoned William Hartnell story called The Phoenix Rises being discovered and used to create a new story featuring the First and Fifth Doctors, which would be made in black-and-white so the Hartnell footage would match seamlessly with the Peter Davison material. The date for the start of filming was "1 April 1983".
 * In issue 88 of Doctor Who Magazine, it was reported by "John Wakefield" — actually the name of the television reporter played by Michael Wisher in The Ambassadors of Death — that not only had "around 95%" of The Tenth Planet episode four been found in a BBC department, but also the story was being colourised for transmission in Canada — apparently due to the country's television transmitters being unable to broadcast black-and-white material. The project's production code was "01:04/84".
 * In 2009, as an April Fool's joke, word circulated around the Doctor Who set that Michael Jackson was paying a visit. (REF: Doctor Who: The Writer's Tale - The Final Chapter)
 * In 2020, the Big Finish Twitter account announced an 18-hour boxset of Tom Baker reading the phonebook.