statue of Oliver Cromwell, by Hamo Thornycroft, 1899. Located outside the Palace of Westminster, London. Oliver Cromwell (25 April 1599 - 3 September 1658), was an English military and political leader. He served as Lord Protector of the Commonwealth of England, Scotland, and Ireland from 1653 until his death, acting simultaneously as head of state and head of government of the new republic.