Middlesex was related by marriage to the families of Bourchier, St. John, Villiers, Fane, Carey and Sackville. He inherited a substantial estate from his brother, including lands in Essex, Gloucestershire, Middlesex and Warwickshire.
No doubt relieved to find some distraction from his woeful domestic situation, towards the end of the Interregnum Middlesex became increasingly involved with conspiracies to restore the monarchy. In September 1658 he conveyed a promise of service to the king and in November was again granted permission to travel abroad, perhaps intending to meet other royalists. Although he seems to have been unwilling to contribute any funds towards the king’s cause in March 1659 (he contracted smallpox at about that time), in July Middlesex joined the fragmented rising initiated by John Mordaunt, Viscount Mordaunt, and was captured at Lincoln.
One of the first lords to enter the restored House, Middlesex, with his brother-in-law Dorset, was among a small group of former royalists who tested the resolve of the other peers by taking their seats on 25 Apr. 1660.
On 14 Aug. he was added to the committee considering the bill for William Cavendish, marquess (later duke) of Newcastle, but two days later he was granted leave to be absent. Returning to the House in November, on the 6th Middlesex was named to the committee for the bill to restore Henry Arundell, 3rd Baron Arundell of Wardour, to his estates and he was also added to that considering Dorset’s bill on 23 November. On 15 Dec. he was named to one further committee during the session, considering the Hatfield level bill.
Middlesex took his seat shortly after the opening of the Cavalier Parliament on 14 May but on the 22nd he was again granted leave to be absent. He resumed his seat on 10 June and was thereafter present for approximately 38 per cent of all sitting days. On 13 June his wife secured an order for their separation from the court of arches, complaining of his cruelty and desertion. On 27 June Middlesex was named to the committee chaired by Dorset considering Sir Anthony Browne’s bill but on 6 July he secured permission from the king to be absent again.
Middlesex returned to the House on 20 Nov. 1661 and on 26 Nov. he was named to the committee for the Quakers’ bill. The following month, on 11 Dec. he was forced to claim his privilege in a case brought against him by Sir William Underhill, under-sheriff of Warwickshire, in the court of common pleas.. Middlesex was named to two further committees during the session: on 8 Feb. 1662 to that considering Sir Aston Cockayne’s bill and on 11 Apr. to the committee for the glass bottles bill, again chaired by Dorset.
Middlesex took his seat at the opening of the second session on 18 Feb. 1663, following which he was present on approximately 37 per cent of all sitting days. His attendance was once more somewhat erratic. On 23 Feb. he was again excused his absence at a call of the House. He resumed his seat two days later when he was named to the committee for petitions and on 11 Apr. he was named to the committee for the Ashdown forest bill, a measure with which Dorset was very closely involved. In May he had to appeal for his privilege to be upheld again when Francis Grimes arrested one of his servants. The previous month had witnessed the beginning of a far more damaging case, when on 14 Apr. Middlesex’s niece, Lady Elizabeth Cranfield, absconded from her grandmother’s house and sought refuge with John Egerton, 2nd earl of Bridgwater. Although Bridgwater claimed to have received the king’s permission to shelter the girl, his letter to Lady Elizabeth’s stepfather, Sir Chichester Wrey‡, explaining his actions failed to defuse the situation, which was further complicated when, on Lady Elizabeth’s behalf, Bridgwater accused Middlesex of failing to abide by the terms of his brother’s will and denying her the £14,000 portion. He also revived the claim that as sole heir of the 2nd earl she was entitled to the entire Cranfield estate.
Middlesex responded to the crisis by issuing a challenge to Bridgwater in (as Bridgwater phrased it) ‘the Billingsgate dialect’ but the intended duel was discovered and prevented when both peers were secured.
The case between the two families continued to be debated in the courts for a further two years, Middlesex pursuing his cause (according to Bridgwater) ‘with as much malice as possible’. It was ultimately settled essentially in Middlesex’s favour, with the recognition of the validity of his father’s and brother’s wills and an order to fulfil the terms laid down in them by paying Lady Elizabeth the stipulated portion when she attained the age of 16.
On 3 July 1663, the day after his humiliating return to the House, Middlesex requested that John Cramphorne, a carman who had ‘affronted’ the lords ‘as they were come to attend the Parliament’ the previous day and who had been taken into the custody of the serjeant-at-arms, might be taken before the lord chief justice and released following the securing of sureties for his good behaviour. Middlesex continued to sit until 17 July but he seems to have taken no further role in the House’s business during the session.
Middlesex took his seat once more on 16 Mar. 1664 and on 21 Mar. he was named to the committee for privileges. On 27 Apr. he was named to the committee considering the bill for Sir John Packington and the inhabitants of Aylesbury but he failed to sit after 11 May. In August, the refusal of Arthur Annesley, earl of Anglesey, to exchange one of his forest walks with Middlesex prompted Prince Rupert, duke of Cumberland, to offer to exchange one of his instead.
Middlesex failed to attend the session of Parliament held at Oxford in 1665. He returned to the House on 18 Sept. 1666 at the opening of the new session but, having attended on a mere four days, on 13 Nov. he registered his proxy in favour of Thomas Belasyse, 2nd Viscount Fauconberg. The proxy was vacated when he resumed his seat on 3 December. He then sat for a further three days before quitting the session.
In June 1667 Middlesex and Charles Howard, earl of Carlisle, were placed in joint command of securing the river defences at Woolwich by order of the king.
On 31 Mar. 1669 Middlesex was granted a pass to go into France.
In March 1672, Middlesex was one of several local landholders to enter a caveat against the new charter for Stratford-upon-Avon.
Rumours circulated that Middlesex had died in September 1673 but he proved to be sufficiently animate to be named a gentleman of the bedchamber the following month. He appears to have owed his appointment to the interest of his nephew, Charles Sackville, styled Lord Buckhurst (later 6th earl of Dorset and Middlesex). In return, he settled his estate on the young man.
Middlesex’s infrequent attendance of the House belies his real influence. At least two undated letters, one of them from Thomas Savage, 3rd Earl Rivers, in which Middlesex’s presence on committees is requested, point to his interest in the House.
