On 7 Dec. 1761 de Grey, solicitor-general to the Queen since September, was returned as an Administration candidate at Newport on Humphry Morice’s interest, and on 16 Dec. applied to Bute for the post of solicitor-general to the King should it become vacant.
In 1768 de Grey was again returned as a Government candidate at Newport, and also on the Townshend interest at Tamworth, but chose to sit for Newport. As attorney-general he presented the Government’s case against Wilkes in 1769 and took a prominent part in the debates in the House.
After Camden’s dismissal in Jan. 1770, Horace Walpole commenting on possible successors to the Great Seal, wrote that de Grey ‘wanted health and weight, and yet asked too extravagant terms’.
By the King’s commands I saw Mr. de Grey, a most able and upright lawyer, and as perfect a gentleman ... In a long conference we had at his house, he appeared inclined to undertake the situation in spite of his frequent attacks of gout.
But next day de Grey, discovering that Grafton soon intended to resign, declined the office. In February 1770, at Grafton’s suggestion, he moved from Newport to Cambridge University and was returned there unopposed. On 12 Nov. 1770 Horace Walpole wrote to Horace Mann: ‘We have ... or shall by tomorrow have a lord chancellor. It is de Grey, the attorney-general, a very proper one, as often as the gout will let him be so.’ But nothing came of this and in Jan. 1771 he became lord chief justice of the common pleas, which vacated his seat.
When in 1778 de Grey’s office was required for Wedderburn who with Thurlow was also to have a peerage, North informed the King on 3 Apr. that de Grey refused to quit the chief justice’s place without a peerage: he ‘has a fortune in possession and expectation equal to a peerage, and ... conceives himself well entitled to any honours that Mr. Thurlow or Mr. Wedderburn can pretend to. Both he and his son complain much of the slur intended to be thrown upon him.’ The King replied the same day: ‘As to the chief justice thinking himself ill-used ... it has not the smallest foundation; I offered him the Great Seal and a peerage. He declined both.’ And on 15 Apr. the King wrote that he had told de Grey that he could not now give three peerages to the legal profession; but would promise him one on the first promotion of others to peerages, or to his son in the case of his death. De Grey gave his ‘hearty acquiescence’ to this. He hoped in addition to obtain an annual pension of £2,500, but the whole arrangement was shelved by Wedderburn’s remaining in the Commons.
He died 9 May 1781.
