oliver cromwell
I think it is odd that a statue of Cromwell was placed outside the Commons, he could hardly be described as a good parliamentarian and he was intolerant of anyone who did not agree with his particular brand of Christianity.
Cutting off the head of Charles 1st did, however, make subsequent monarchs very wary of obstructing legislation!
I can imagine King Charles 111 fiddling with his cufflinks for a very long time when some irksome legislation is placed before him to sign.