The story
From Mrs + Miggins (a surname), possibly popularized by the character Mrs Miggins who is mentioned in the British television comedy series Blackadder II (first broadcast 9 January – 20 February 1986) as the owner of a pie shop, and appears in Blackadder the Third (17 September – 22 October 1987) as a coffee shop proprietress.
Etymology from Wiktionary, CC BY-SA 4.0.