The Council of State provided the executive government of the Commonwealth directing home and foreign policy and carrying out the orders of Parliament. The members of the first Council of State were appointed by the Commons on 14 Feb 1649 and 15 Feb 1649 [1], with further annual elections. The Council held its first meeting on 17 Feb 1649 "with Cromwell in the chair". This meeting was quite rudimentary, "some 14 members" attending, barely more that the legal quorum of 9 (out of 41 members). In full formal style the Council was "Council of State appointed by Authority of Parliament," and sometimes "Keepers of the Liberties of England by the Authority of Parliament." After the dissolution of the Rump Parliament (20 Apr 1653), Cromwell told the Council that it no longer existed and together with the Council of Officers, instituted a new Council of State (30 Apr 1653). Following the dissolution of the Nominated Assembly (16 Dec 1653), the Council of State was modified under the Instrument of Government, 1653, the first written Constitution of the Commonwealth. Between 13 and 21 councilors were elected by Parliament to advise the Lord Protector Oliver Cromwell. The Council was modified again under the Humble Petition and Advice 1657, another constitution, which granted almost monarchical powers to Cromwell and which authorized him to choose 21 Privy Councilors himself. Being legally invested with exercising executive authority on instructions from the Parliament, the Council of State remained a sole bearer of constitutional power when the Parliament was prevented from sitting at Westminster by the military (13 Oct 1659); temporarily restored public order by sending orders to the troops to return to their quarters (13 Oct 1659); due to the confrontation with the Council of Officers and amidst general anarchy, ceased to administer political affairs with degrading attendance at meetings; was dissoled and superseded by the Council of Safety, consisting of army officers and civilians nominated by the Council of Officers (25 Oct 1659). As the Parliament was allowed to meet again on 26 Dec 1659, it decided to elect a new 31-member Council of State to hold the offices from 1 Jan 1660 to 1 Apr 1660. The election followed on 30 Dec 1659 and 31 Dec 1659 and the names of the members were publicly announced during the sessions of 31 Dec 1659 and 2 Jan 1660. The authority of the Council was derived from an Act, with Instructions to be given to the Council of State (passed 2 Jan 1660). The restoration of the Long Parliament by General Monck (21 Feb 1660) prompted passing of a resolution for suspension of the powers given to the Council of State (21 Feb 1660). The Parliament proceeded with elections (23 Feb 1660) and passed an An Act for constituting a Council of State (25 Feb 1660), which was elected for the period "until the Parliament take further Order." The Council was authorized to exercise executive authority between the dissolution of the Parliament (16 Mar 1660) and meeting of a Parliament at Westminster (25 Apr 1660) in accordance with an Act for giving Power to the Council of State, during the Interval, in Order to publick Safety (passed 15 Mar 1660). The Council of State continued to sit during the Convention Parliament, which first met on 25 Apr 1660. President of the Council, Arthur Annesley, participated in solemn ceremony of the proclamation of Charles II (8 May 1660). The Council was engaged into proceedings against the regicides and was not dissolved until 28 May 1660 when the king entered London to assume the government in person.

A proposal for appointing a Lord President of the Council of State was rejected by the Commons (16 in favor; 22 against) on 15 Feb 1649 [1, p. 143]. Oliver Cromwell signed the Council documents from 17 Feb 1649 to 12 Mar 1649 as praeses pro tempore. However, there were sessions of the Council at which Cromwell was absent; e.g., on 27 Feb 1649 Denbigh was in the chair and was acting for Cromwell. In 1659, presidents served for very brief periods and the evidence from signatures as president seems to be quite confusing. It is known that Bulstrode Whitelock served as President at the "closing" of the Parliament by the Army 13 Oct 1659 and until the Council was dissolved 25 Oct 1659.