Rump Parliament (The Roundheads) was the name given to the state of the English Parliament after Colonel Thomas Pride and Lord Grey of Groby repelled all Parliament members opposing the trial and possible execution of King Charles I, such as Presbyterians and Levellers. (PROSE: The Roundheads)
Behind the scenes
The term Rump Parliament itself is never used in the story. However, one of the characters says "the rump of this Parliament" and the word Rump is sometimes capitalised when applied to the Parliament.