In April 1640, Gardiner was elected Member of Parliament for Callington in the Short Parliament. He was an unsuccessful Royalist candidate for the city of London. In 1642 he was leading counsel to Sir Edward Herbert, when he was impeached. Gardiner was himself impeached soon after for his support of ship-money. He was solicitor-general to the king at Oxford in 1643. He was a Royalist commissioner at the Treaty of Uxbridge and Royalist attorney-general in 1645. He was pardoned by parliament in 1647 on payment of fine.
His daughter Mary was Maid of Honour to Queen Henrietta Maria in France, and one of the four Dressers to Queen Catherine after the Restoration, before marrying Sir Henry Wood, 1st Baronet. She died of smallpox on 17 March 1671, aged 38, and was buried in Westminster Abbey. In 1679 her only child married an illegitimate son of King Charles II by Barbara Villiers, becoming Duchess of Southampton, but died of smallpox in 1680 at the age of seventeen.
|Parliament of England|
Parliament suspended since 1629
| Member of Parliament for Callington
With: Samuel Rolle
Sir Arthur Ingram