On the expulsion of the Rump Parliament on 20 April 1653 by Oliver Cromwell, lord general of the army, supreme power in the nation rested with Cromwell himself. An assembly was called which first met in July, and which adopted the title of parliament, even though none of its members was elected. It began life as a radical assembly, which pursued reforming legislation of which Cromwell at that point in his career approved. Its title comes from the surname of one of its members who represented London, even though he played no particularly significant role in its proceedings. After a short while, it became evident that the membership of this parliament had become more divided politically than Cromwell and his advisers had anticipated, and on 12 December, a majority of the members surrendered their authority to Cromwell, who immediately put in hand plans to inaugurate a protectorate.
At the time of the summoning of the Barebones Parliament, Cromwell was sympathetic to the optimism of those radical protestants in political life known as millenarians. They believed that the creation of a commonwealth in which godly values prevailed was possible, and Cromwell was open to the suggestion that difficulties with earlier parliaments could be overcome if the members were hand-picked instead of being sent to Westminster by the usual uncertainties of parliamentary elections. Some members were recommended by ‘gathered’ congregations, that is, churches which appointed their own ministers and managed their own affairs; others were known to t