prince's eventually attaining the English throne.
Early in December 1680, after the rejection of the Exclusion Bill in the lords, Sidney forwarded to the king from the Prince of Orange a Dutch memorial of remonstrance. Sunderland wrote to him on 7 Dec. announcing how the paper had been received at the council. ‘The king was very angry at it, thinking the states ought not to have spoken so plainly and particularly.’ The secretary was ordered to give Sidney a caution with regard to the forwarding of such documents, and, a few months later, in June 1681, the envoy received letters of revocation. He claimed to have done the king special honour by living more like an ambassador than an envoy for as long as his mission lasted. Contrary to expectation, Charles received him kindly at Windsor on 23 June, and shortly afterwards, in accordance with the Prince of Orange's wish, he was appointed general of the British regiments in the service of Holland. He held this post until a few weeks after the accession of James, but the latter does not seem at the first to have distrusted him, as, after Monmouth's rebellion, he was sent back with Bentinck on a mission to the Hague. During 1686–7 he kept himself out of harm's way by travelling in Italy. Early in 1688, however, he was back again in England, and had renewed a long-standing intrigue with the wife of his nephew Sunderland.
In the meantime, unsuspected by the court, he was pursuing negotiations of the utmost moment. The fact that Sidney had the Prince of Orange's confidence was well known to the latter's friends in England. Though indolent and dissolute, he possessed in a rare degree the instinct of intrigue, and Burnet is probably correct in his statement that in Sidney's hands the ‘whole design’ of the invitation to the Prince of Orange was ‘chiefly deposited.’ Of his coadjutors the most prominent seems to have been Edward Russell, earl of Orford [q. v.] His success was so great that from those whom he sounded he received only one dubious answer, Halifax. He got permission to leave England, on condition of not visiting the prince, at the end of August. Disregarding his pledge, he went almost directly to the Hague in company with Zulestein, who was returning thither from the English court, whither he had been sent to congratulate James upon the birth of a son and heir. Sidney bore with him a duplicate copy of the invitation and declaration of adherence to William, signed by the members of the association which he had formed, and including the names of Danby, Shrewsbury, Devonshire, Lord Lumley, the bishop of London (Compton), and Admiral Russell. He conveyed, moreover, the secret assurances of Marlborough; while Sunderland, far from resenting his uncle's intimacy with his wife, made the countess (who communicated everything in cipher to Sidney) the medium of secret intelligence of the utmost value to William.
Together with Schomberg, Burnet, and Herbert, Sidney accompanied the expedition to Torbay. In the events of the next three months he took only a secondary part. On the day after the proclamation of William and Mary, however, he was appointed of the privy council (14 Feb. 1689), two weeks later a gentleman of the bedchamber, and on 16 March a colonel of the king's regiment of footguards. He had been returned for Tamworth in the Convention parliament, but on 9 Sept. he was raised to the peerage as Baron Milton, co. Kent, and Viscount Sydney of Sheppey. He was lord lieutenant of Kent from 1689 to 1692, and again from 1694 to 1704. He accompanied William to Ireland in 1690, was present at the Boyne, and was made one of the lords justices after having received confiscated estates, nearly 50,000 acres in extent, and to the value, it is said, of 17,000l. per annum. In December 1690 he was summoned back to England, and, to the profound mortification of Danby, now earl of Caermarthen, entrusted with the seals as secretary of state. At first Danby could hardly believe in the appointment of a person of a character so facile. When William asked him if he had met the new secretary, leaving his presence, he answered, ‘No, sir! I met nobody but my Lord Sidney.’ ‘He is the new secretary,’ said the king; ‘he will do till I find a fit man; and he will be quite willing to resign when I find such a man.’ Caermarthen remarked that it was new to see a nobleman placed in such an office as a footman was placed in a box at a theatre, merely in order to keep a seat till his betters came ({{sc|Dartmouth, Note on Burnet, ii. 5). True to his purpose, William called upon Sidney to deliver up the seals in little more than a year, and in March 1692 he was sent as lord lieutenant and governor of Ireland, a post of extreme difficulty, in the conduct of which he egregiously failed. The Irish parliament, having been summoned to assemble on 5 Oct. 1692, at once began clamouring against the indulgence meted out to the Irish catholics. Alarmed by their factious energy in the formation of grievance committees, Sidney, after a session of barely six weeks, dissolved the parliament on the ground that they were infringing the Poynings statute (An Account of
