Restoration
On 29 July 1660, Gerard received a grant in reversion of the office of Remembrancer of the Tenths and First-Fruits. On 13 September his estates, which had been forfeited by Parliament, were restored to him.
On 15 May 1661, Gerard petitioned for the post of ranger of Enfield Chase, which he obtained. His title, however, was disputed by the late ranger, James Cecil, Earl of Salisbury, and he was soon involved in litigation with Captains Thomas and Henry Batt, keepers of Potter's Walk and bailiffs of the Chase, whose patents he refused to recognise. Both matters were referred to the lord chancellor for decision. As against the Batts, Gerard succeeded on the technical ground that their patent was under the great seal, whereas by statute it should have been under that of the duchy of Lancaster. It does not appear how the question with the Earl of Salisbury was settled.
In 1662 Gerard was granted a pension charged on the customs. Towards the end of the year, he was sent as envoy extraordinary to the French court, where he was very splendidly received. About this time he became a member of the Royal African Company, which obtained in January 1663 a grant by letters patent of the region between Port Sallee and the Cape of Good Hope for the term of one thousand years. Litigation in which he was this year engaged with his cousin, Alexander Fitton, afterwards Lord Chancellor of Ireland, was watched with much interest by his enemies. The dispute was about the title to the Gawsworth estate in Cheshire, of which Fitton was in possession, but which Gerard claimed. The title depended on the authenticity of a certain deed which Gerard alleged to be a forgery, producing the notorious forger Alexander Granger, who swore that he himself had forged it. Gerard obtained a verdict at the Chester assizes and ejected Fitton. Fitton, however, published a pamphlet in which he charged Gerard with having procured Granger's evidence by intimidation. Gerard moved the House of Lords on the subject, and the pamphlet was suppressed. Fitton was imprisoned for scandalum magnatum, the offence of libelling a peer: he remained in prison for almost 20 years.
In March 1665 Gerard was granted a pension of £1,000 per annum to retire from the post of captain of the guard, which Charles desired to confer on the Duke of Monmouth. His retirement, however, did not take place until 1668, when Samuel Pepys says that he received £12,000 for it. Pepys also states that it was his practice to conceal the deaths of the troopers that he might draw their pay; and one of his clerks named Carr drew up a petition to the House of Lords charging him with peculation to the extent of £2,000 per annum. The petition found its way into print before presentation, and was treated by the house as a breach of privilege, voted a "scandalous paper", and ordered to be burned by the common hangman. Carr was sentenced to pay a fine of £1,000, to stand in the pillory for three hours on each of three different days, and to be imprisoned in the Fleet during the king's pleasure. Gerard subsequently indicted him as a deserter from the army.