1552 he was one of the three commissioners appointed to exercise the functions of lord lieutenant of Norfolk and Suffolk, and his appointment was renewed on 24 May 1553. He was one of the witnesses to Edward VI's settlement of the crown on Lady Jane Grey, but, not being a privy councillor, did not sign the engagement to carry it out. He gave in his adhesion to Mary on 17 July, securing by his promptness the favour of the queen, who at once made him one of her privy councillors, and bestowed on him a greater mark of confidence by appointing him one of the commissioners to examine Northumberland, Northampton, and Lady Jane Grey. He was one of the peers who tried Northumberland on 17 Aug., and the minor conspirators on the following day.
On 13 Sept. following Wentworth was by letters patent appointed deputy of Calais (Dep. Keeper of Records, 4th Rep. App. ii. 259), but he did not assume the duties of his office until December. He was the last English deputy of Calais, and, with the exception of a visit to England in March to May 1556, remained at his post until its capture by the French. Soon after his arrival Wentworth represented to the council the defenceless state of Calais, but no effective steps were taken to strengthen it (Acts P. C. 1556–8, p. 91). Late in the autumn of 1557 Guise laid plans for the seizure of the town by a coup-de-main. On 18 Dec. news of this project reached Wentworth, but he neglected the warning until it was confirmed on the 26th. On the following day a council of war was held, and it was decided to abandon the open country, and only attempt the defence of Guisnes, Hammes, Newhaven (Haven Etue), Rysbank, and Calais. Reinforcements were ordered from England under the Earl of Rutland, but on the 29th Wentworth wrote that Calais was in no immediate danger; he disbelieved alike the French reports and the warnings of Lord Grey de Wilton, who was captain of Guisnes. On the 31st Guise's army arrived on the borders of the Pale, and on 1 Jan. 1557–8 Rutland was again ordered to proceed at once to Calais. He failed to arrive in time; one fortress after another fell before Guise; on the 6th the castle of Calais was surrendered, and on the 7th Wentworth yielded up the town, being himself one of the prisoners of war.
It was well for Wentworth that he was kept away from England for a time; for the loss of the last stronghold on the continent produced an outbreak of indignation that would certainly have cost him his head, and he would have been a convenient scapegoat for the government. On 2 July 1558 he was indicted for having on 20 Dec. 1557 become an adherent of the French king, and conspired to deliver Calais into his hands, of having neglected to take any musters or make any levies for its defence, and on 15 July orders were given for sequestering his estates and taking an inventory of his goods. Wentworth, however, prudently remained in France, and was not ransomed till after the change of government. He returned in April 1559, and on the 21st was committed to the Tower. Northampton had on the 20th been appointed lord high steward for his trial for high treason; it took place before a panel of his peers on the 22nd, and Wentworth was acquitted (‘Baga de Secretis’ in Dep.-Keeper of Records, 4th Rep. App. ii. 259–61; Machyn, Diary, p. 195; Hayward, Annals, p. 36; Wriothesley, Chron. ii. 144). There was indeed no evidence that Wentworth was a traitor, and Elizabeth was no doubt averse from marking the commencement of her reign with bloodshed; but it is evident that Wentworth's incompetence contributed materially to the loss of Calais, and he was at least as culpable as his subordinates, Sir Ralph Chamberlain, lieutenant of the castle of Calais, and John Harleston, lieutenant of Rysbank, who were condemned for treason on 1 and 22 Dec. 1559, though their lives were spared. In an elaborate article in the ‘North British Review’ (December 1866), based on unpublished archives at Brussels and Paris, the entire blame of the catastrophe is put upon Wentworth, who is described as ‘a man of small capacity, of no energy, of great arrogance and conceit, and withal unmindful of his duties.’ It should, however, be remembered that Wentworth had repeatedly pointed out the condition of Calais to the government, which had persistently neglected his warnings.
Wentworth failed to obtain any important employment under Elizabeth. He was, however, appointed lord lieutenant of Norfolk and Suffolk, and frequently served as commissioner for musters and for the good government of the city of London (Acts P. C. 1558–80 passim). On 8 Sept. 1560 he was one of those ordered to receive the king of Sweden, and in January 1572 was one of the peers who tried the Duke of Norfolk. In 1561 was dedicated to him the English translation of Bullinger's ‘Sermons.’ He died at Stepney on 13 Jan. 1583–4. A portrait of Wentworth belonged in 1779 to Thomas Noel, viscount Wentworth, and was engraved for the ‘Antiquarian Repository’ (1808, iii. 59); another belonged in 1866 to Mr. F. Vernon-Wentworth of Wentworth Castle (Cat. First Loan Exhib. No. 178).
