E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Oliver Cromwell (1648) sent two regiments to the House of Commons to coerce the members to condemn Charles I. Forty-one were seized and imprisoned in a lower room of the House, 160 were ordered to go home, and the sixty favourable to Cromwell were allowed to remain. These sixty were merely the fag-end or rump of the whole House. (See PRIDES PURGE.)
The name was revived again in the protectorate of Richard Cromwell. Subsequently the former was called The Bloody Rump, and the latter The Rump of a Rump.