Long Meg of Westminster
A acted virago in the reign of Henry VIII. Her name has been given to several articles of unusual size. Thus, the large blue-black marble in the south cloister of Westminster Abbey, over the grave of Gervasius de Blois, is called “Long Meg of Westminster.” Fuller says the term is applied to things “of hop-pole height, wanting breadth proportionable thereunto,” and refers to a great gun in the Tower so called, taken to Westminster in troublous times.
The large gun in Edinburgh Castle is called Mons Meg, and the bomb forged for the siege of Oudenarde, now in the city of Ghent, is called Mad Meg.
In the Edinburgh Antiquarian Magazine, September, 1769, we read of “Peter Branan, aged 104, who was six feet six inches high, and was commonly called Long Meg of Westminster.” (See Meg.)
“This, and the Robrick stones in Oxford shire, are supposed to have
been erected at the investiture of some Danish kings, like the
Kingstoler in Denmark, and the Moresteen in Sweden.” —
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894
More on Long Meg of Westminster from Infoplease: