Spanning the period May 1649 to June 1673, the papers include correspondence, commissions and official instructions, proposals for treaties with various European heads of state, reports and dispatches. All relate to the Dutch Wars of 1652-1654, 1665-1667 and 1672-1674. The collection has been catalogued to preserve the ordering of the papers as the Clifford family had arranged them, and follows a roughly chronological sequence.

Administrative / biographical background
Thomas Clifford was born at Chudleigh, near Exeter, Devon on 1 August 1630. He matriculated at Exeter College, Oxford in 1647 and then entered the Middle Temple in the following year to complete his education. In November 1664, on the eve of the Second Dutch War, Clifford was made a Commissioner for Sick and Wounded Seamen and Prisoners of War. On 14 January 1665, he was appointed as Sub-Commissioner for Prizes for the Port of London, rising to the position of General Commissioner on 24 March. In the same year, Clifford also received a knighthood and joined the English Fleet at sea participating, with the Duke of York, in the Battle of Lowestoft on 3 June. On 28 June, Charles II granted him the prize ship the PATRIARCH ISSACK, captured from the Dutch, for attention to his duties as Sub-Commissioner for Prizes for the Port of London. In August of that year he was again at sea as Captain of the REVENGE, serving under the Earl of Sandwich at the Battle of Bergen. On 29 August 1665, Clifford was appointed, with Sir Henry Coventry, as Extraordinary Envoy to Sweden and, with Sir Gilbert Talbot, as Extraordinary Envoy to Denmark, to settle questions of commerce and navigation. Sir Clifford was to see direct action again in the Second Dutch War, between 1 and 4 June 1666, when he participated in the Four Days' Battle, and on 25 July 1666 at the St James Day Battle. On 8 November that year, he was appointed Comptroller of the Household and on 5 December he was placed on Charles II's Privy Council. As one of the King's most trusted advisors, he subsequently received a number of high profile appointments, the first in 1667, when he was asked to serve on the Commission of the Treasury. In October 1667, he was requested to assist in the preparation of a report on the English Fleet at war. He was made Treasurer of the Household on 14 June 1668. In 1670, Sir Clifford was responsible, with other ministers including the Earl of Arlington, for the negotiation of the Secret Treaty of Dover of June 1670 with Louis XIV of France, urging Charles II to go to war with the United Provinces. Two years later, during the absence of Coventry and Arlington in Sweden and Holland, Clifford was appointed as Principal Secretary of State. In April 1672, he was created 1st Baron Clifford of Chudleigh and on 28 November was appointed as Lord High Treasurer. The same year he was also made Treasurer of the Exchequer, and was a principal promoter of the Declaration of Indulgence of 1672, suspending penal laws against dissenters and Catholic recusants. Clifford was a member of the Cabal, a group of inner advisers to Charles II, which included Clifford, Ashley (Lord Shaftesbury), Buckingham (George Villiers), Arlington (Henry Bennett) and Lauderdale (John Maitland). Their initials form the word, although the origin of the term is much earlier. Although never a working ministry, one or more of this group was to dominate Court policy from 1667-1673. After the Test Act of 1673, Clifford as a Roman Catholic was forced to resign his role as Treasurer and in June he left the Privy Council. He died, possibly by his own hand, in September of the same year.