Maynard, Sir William Jones, Sir Francis Winnington, and George Treby. Stafford, who was only allowed to consult his counsel when points of law arose, defended himself with greater ability than was anticipated. Dugdale, Gates, and Turberville all bore false witness against him. Gates declared that he had delivered a commission to him from the pope as paymaster-general of the army which ‘was to be raised for the promoting of the catholic interest’ (State Trials, vii. 1348). Dugdale and Turberville both swore that Stafford had endeavoured to persuade them to murder the king (ib. pp. 1343, 1353). Stafford vainly protested his innocence. The legal objection raised by him ‘touching the necessity of two witnesses to every overt act as evidence of high treason’ after the opinion of the judges had been taken upon the point was overruled (ib. pp. 1525-33). On 7 Dec. Stafford was found guilty by 55 to 31, and sentence of death by hanging, drawing, and quartering was pronounced by Finch, who had shown considerable courtesy and fairness to the prisoner during the trial. According to Evelyn, Stafford ‘was not a man beloved especially of his own family’ (Diary, ii. 154), and all his kinsmen who took part in the trial found him guilty with the exception of Lord Mowbray, afterwards seventh duke of Norfolk. At Stafford's request Burnet and Henry Compton, the bishop of London, visited him in the Tower, and to them he solemnly protested his innocence. On 18 Dec., having promised to discover all that he knew, Stafford was taken before the House of Lords, where ‘he began with a long relation of their first consultations after the Restoration about the methods of bringing in their religion, which they all agreed could only be brought about by toleration. He told them of the Earl of Bristol's project, and went on to tell who had undertaken to procure the toleration for them; and then he named the Earl of Shaftsbury. When he named him he was ordered to withdraw, and the lords would hear no more from him’ (Burnet, Hist. ii. 272; see also Hist.MSS. Comm. 11th Rep. pt. ii. pp. 43-4).
Stafford was beheaded on Tower Hill on 29 Dec. 1680, the king remitting the other barbarous penalties. The question whether this remission lay in the power of the king gave rise to a short debate in the House of Commons (Parl. Hist. iv. 1260-1). While on the scaffold Stafford read a speech, in which he again protested his innocence (State Trials, vii. 1564-7). He was buried in the chapel of St. Peter ad Vincula in the Tower on the same day, but the exact spot is unknown.
Stafford left three sons and six daughters. His widow was created on 5 Oct. 1688 Countess of Stafford for her life, and died on 13 Jan. 1694. Their eldest son, Henry Stafford Howard, was also on 5 Oct. 1688 created Earl of Stafford, with remainder in default of male issue to his brothers. Upon the abdication of James II he retired to France, where on 3 April 1694 he married Claude Charlotte, the eldest daughter of Philibert, comte de Grammont, and died 27 April 1619 without issue. On the death of John Paul Stafford-Howard, the fourth earl, on 1 April 1762,. this earldom became extinct.
On 27 May 1685 a bill for reversing Stafford's attainder was read for the first time in the House of Lords. Though it passed through the lords and was read a second time in the House of Commons (6 June), it was dropped upon the outbreak of the Duke of Monmouth's rebellion. In the beginning of the present century some abortive proceedings were taken before the committee of privileges by Sir William Jerningham, and subsequently by his son Sir George William Jerningham, descendants of Mary Plowden, Stafford's grand-daughter (House of Lords' Papers, 1808 No. 80, 1809 No. 107, 1812 No. 18). At length in 1824 ‘an act for reversing the attainder of William, late viscount Stafford,’ was passed (5 Geo. IV, c. 46; private act not printed). On 6 July 1825 the House of Lords resolved that Sir George William Jerningham had established his claim to the barony of Stafford, created 12 Sept. 1640 (House of Lords' Papers, 1825, No. 129: and Journals, lvii. 1293), and on 1 May 1829 he took his seat for the first time.
A portrait of Stafford by Vandyck belongs to the Marquis of Bute, engraved in Lodge's ‘Portraits,’ vol. vi. A similar portrait is in the possession of the Duke of Norfolk (cf. Howard, Howard Family, p. 36). Stafford's town residence was Tart Hall, ‘without the gate of St. James's Park’ (Cunningham, Handbook for London, 1849, ii. 797-8).