He served as secretary to Edward la Zouche and the Duke of Buckingham in the Admiralty and became a clerk of the Privy Council.

He supported the Royalist cause in the English Civil War and accompanied the court into exile, before assuming the post of Secretary of State on the Restoration.

[1] 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.

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.

He also had the duty of treating for the capitulation of Oxford on 24 June 1646, which included permission for Nicholas himself to retire abroad with his family.

[2] 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.

[1] As an enthusiastic Royalist, in a letter dated 10 September 1657 to Sir Edward Hyde, Nicholas speaks of Cromwell, ...

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.