Letterbox

The Dalek Survival Guide presented a slightly different version of the Emperor Type 1 casing sighted in the 1963 Shoreditch Incident, claiming that its vision systems were linked to a letterbox-shaped panel in the dome section. (PROSE: Dalek Survival Guide)

Upon her return on 6 March 2006, Mickey Smith told Rose Tyler that he had got "stuff through [his] letterbox" as he was accused of being responsible for her disappearance twelve months prior. (TV: Aliens of London)