Nicholas was the eldest son of John Nicholas of a Wiltshire family. He was educated at Salisbury grammar school, Winchester College and Queen's College, Oxford. After studying law at the Middle Temple, in 1618 Nicholas became secretary to Edward la Zouche, 11th Baron Zouche, lord warden and admiral of the Cinque Ports. In 1621 he was elected as a Member of Parliament for Winchelsea. He was re-elected as one of the Members for Winchelsea in 1624 for what became known as the Happy Parliament. Nicholas kept diaries of all the parliaments in which he sat. When Zouche resigned his office of lord warden to the Duke of Buckingham, the Duke, upon Zouche's recommendation, on 9 December 1624 appointed Nicholas as his secretary for the business of the Cinque Ports. In 1625 Nicholas became the first holder of the office of Secretary to the Admiralty; shortly afterwards he was appointed an extra clerk of the privy council, with duties relating to Admiralty business. In 1628 he was elected a Member for Dover and sat until 1629, when King Charles decided to rule without parliament and in the event did so for eleven years. Appended to a copy of Charles's speech at the dissolution of this parliament on 10 March 1629 is a poem of twenty-four verses in Nicholas's hand, beginning:
From 1635 to 1641 Nicholas was one of the clerks in ordinary to the council. In this situation he had much business to transact in connection with the levy of ship-money. When in 1641 King Charles I went to Scotland, he remained in London and was responsible for keeping the king informed of the proceedings of parliament. When Charles returned to London, Nicholas was knighted and appointed a privy councillor and a Secretary of State, in which capacity he attended the king while the court was at Oxford and carried out the business of the Treaty of Uxbridge. Throughout the Civil War, Nicholas was one of Charles's wisest and most loyal advisers. He arranged the details of the king's surrender to the Scots, although he does not appear to have advised or even to have approved of the step. He also had the duty of treating for the capitulation of Oxford, which included permission for Nicholas himself to retire abroad with his family. He went to France, being recommended by the king to the confidence of the Prince of Wales. In 1648 Nicholas wrote a pamphlet, , which called for the readmission of the Jews to England. It is one of the few examples of pro-admission writing that does not also call for the conversion of the Jews and is cited by Menasseh Ben Israel in his Humble Addresses, although Cecil Roth wonders whether the pamphlet might actually have been written by a Jew. After the king's death, Nicholas remained on the continent, concerting measures on behalf of the exiled Charles II with Hyde and other royalists, but the hostility of Queen Henrietta Maria deprived him of any real influence in the counsels of the young sovereign. He lived at the Hague and elsewhere in a state of poverty which hampered his power to serve Charles, but which the latter did nothing to relieve. Charles appointed him secretary of state while in exile in 1654. As an enthusiastic Royalist, in a letter dated 10 September 1657 to Sir Edward Hyde, Nicholas speaks of Cromwell,
... I conceive his Majesty should do well to set a good price on his head and all the heads of the chief commanders in Ireland and also in Scotland...
Nicholas returned to England at the Restoration and duly took office as Secretary of State along with William Morice, a former parliamentary supporter. Nicholas was soon retired, much against his own wishes, in favour of Charles's favourite Henry Bennet. He received a grant of money and the offer of a peerage, which he felt too poor to accept. He retired to a country seat in Surrey which he purchased from Carew Raleigh, son of Sir Walter Raleigh, and there he lived till his death in 1669.
Family
Nicholas married Jane Jay, a daughter of Henry Jay, an alderman of London and had several sons and daughters. His eldest son was Sir John Nicholas, a Clerk of the Signet and Clerk of the Privy Council. His daughter Susannah married as his second wife the Irish statesman George Lane, 1st Viscount Lanesborough: like her father he spent years in exile with Charles II, and by 1659 the couple were almost destitute, but was well rewarded after the Restoration. Susannah died in 1671. His younger brother Matthew Nicholas was successively Dean of Bristol, canon of Westminster and Dean of St Paul's. His country seat was at Sunninghill in Berkshire.
Correspondence
The collected correspondences of Nicholas were published in three volumes by the Royal Historical Society in 1920.
