Tom o' Bedlam n. Formerly, a wandering mendicant discharged as incurable from Bethlehem Hospital, England; hence, a wandering mendicant, either mad or feigning to be so; a madman; a bedlamite.
... the rebels call it, and so may be hanged without judge or jury, wherever they catch me; and they may hang me if they will, for they can never make any thing of me but a King's trooper, or else a Tom o' Bedlam." ... — The Loyalists, Vol. 1-3 - An Historical Novel • Jane West