According to 'Brewer's' the 1840's version of the paddy wagon derived from Maria Lee, a big black Mama who kept a lodging house, The police used to call on her for assistance sometimes to help apprehend ne'er-do-wells. Town was Boston - [U.S I guess].
According to Jonathan Clements in 'Crazy - but True', it is named after Mrs. Maria Manning. With the help of her husband she murdered their lodger, and was executed at Horsemonger Lane jail at Southwark in 1849 - wearing heavy black clothing for the occasion.