MOSTYN, Sir Roger, 3rd Bt. (1673-1739), of Mostyn Hall, Holywell, Flints.

Published in The History of Parliament: the House of Commons 1690-1715, ed. D. Hayton, E. Cruickshanks, S. Handley, 2002
Available from Boydell and Brewer



Dec. 1701 - 1702
1702 - 1705
1705 - 1708
1708 - 1713
1713 - 1715
1715 - 1734

Family and Education

b. 31 July 1673, 1st s. of Sir Thomas Mostyn, 2nd Bt.†, of Gloddaeth, Caern. and Mostyn Hall by Bridget, da. and h. of Darcy Savage of Leighton, Cheshire; bro. of Thomas Mostyn*.  educ. Jesus, Oxf. 1690.  m. 20 July 1703 (with £7,000), Lady Essex Finch (d. 1721), da. of Daniel Finch†, 2nd Earl of Nottingham, sis. of Daniel, Ld. Finch*, 6s. (2 d.v.p.) 6da.  suc. fa. as 3rd Bt. 14 June 1692.1

Offices Held

Sheriff, Caern. 1700–1; custos rot. Flints. 1716, ld. lt. 1727–d.2

Constable, Flint Castle 1701–5, 1715–28; paymaster of marines 1711–Oct. 1714; teller of Exchequer Dec. 1714–June 1716.3


A man of scholarly interests, who maintained and increased his father’s collections of manuscripts and coins, and who was a regular patron of the Welsh antiquarian Edward Lluyd, Mostyn enjoyed a wide circle of acquaintances among clergy and virtuosi. Although he did not take his degree, he kept up his university contacts, especially with Christ Church men like George Smalridge, whose High Churchmanship he shared. His sons were in due course enrolled at Westminster and Christ Church. While he supported from afar the protests of the gentry of north Wales to the Treasury in May 1695 against the proposed grant to Lord Portland, his involvement in public affairs did not yet extend to any parliamentary ambitions. The reason may have been partly financial. For all the breadth of his estate, spread across three counties, and the potential richness of the collieries on his Cheshire property, he was in some financial embarrassment at the time of his marriage in 1703. Two years previously, during unsuccessful negotiations for a marriage to a daughter of the Earl of Derby, it was reported that Mostyn’s estate was worth £5,000 p.a., but it seems that his own extravagance, and in particular his love of horse-racing, led him into financial difficulties. At any rate, in 1696, rather than aiming at Westminster, his thoughts lay ‘towards travelling or marriage’, and at the 1698 election it was his younger brother Thomas who was returned to Parliament.4

Mostyn served as sheriff of Caernarvonshire during the January 1701 election, and during the following summer was appointed constable of Flint Castle, which during the Civil War his grandfather had held for the Royalists. At the next election, having been defeated at the poll in Cheshire, he took his turn as knight of the shire for Flint, an honour which customarily rotated among the leading Tory families of the county, and was classified with the Tories in Robert Harley’s* list of this Parliament. In his first session he assisted in the management of four private bills, two of them in connexion with the Irish forfeitures (on behalf of Philip Savage and Under-Secretary John Ellis*). He was a teller twice: against referring to a committee a petition from some army officers to be allowed interest on the debentures with which part of their arrears had been paid (6 Feb. 1702); and to recommit the bill for the reconstruction of the pier at Whitby (2 Apr.). His party-political allegiance was demonstrated when he was listed among those who had favoured the motion of 26 Feb. vindicating the proceedings of the Commons in the impeachments of the four Whig lords.5

Elected for Cheshire on the Tory interest in 1702, Mostyn naturally opted to sit for a county rather than as the Member for Flint Boroughs, where he had also been returned with the help of (Sir) Thomas Hanmer II* (4th Bt.). The first of seven tellerships in the 1702–3 session came on 10 Nov. 1702 when he told against taking into custody the under-sheriff of Merioneth for failing to return the election writ. He was closely involved with the promotion of the first occasional conformity bill. On 9 Dec., ‘like a little BD [?Bachelor of Divinity]’, he moved the order of the day, to adjourn all public business, in order to enable the bill to be discussed, and he acted as a teller against going into a committee of the whole on the land tax bill. He told again on 11 Dec., against taking into consideration the Queen’s message concerning the Duke of Marlborough’s (John Churchill†) grant, and twice more on the 23rd, first against giving leave for a bill to resume King James II’s grants, and then against a second Whig motion, for a place bill, after which he was nominated to the committee to bring in the Tory alternative, a measure to impose a landed qualification on Members. He continued in the eye of controversy with a motion on 30 Dec., in the debate on the proposed pension for Prince George, to make the prince ‘King’, a ‘bomb’ that another Tory had to defuse. A teller on 5 Jan. 1703 for a High Tory amendment to the resolution for addressing in support of an increase in land forces, to limit English financial liability, he was appointed to the committee to prepare this address, and on 7 Jan., when it was reported, told in favour of recommitting it. His last tellership of the session was on 28 Jan., on the Tory side in a division on the Plympton Erle election, and he voted on 13 Feb. in opposition to the Lords’ amendments to the bill for enlarging the time for taking the oath of abjuration.6

In February and March 1703, and again in July, it was rumoured that Mostyn would be included in a block creation of peers. His aggressive parliamentary style may well have attracted attention, but it is more likely that he owed this rapidly achieved eminence to his broad acres, and to his imminent marital connexion with Secretary Nottingham. As early as January 1703 Nottingham had intervened to try to expedite the issue of a new commission of the peace for Flintshire, remodelled on Mostyn’s and Hanmer’s recommendation, and in July Mostyn married one of the Earl’s daughters, to whom he had originally been introduced by his kinsmen the Leghs of Lyme. Socially, he was the least elevated of Nottingham’s sons-in-law, and although potentially wealthy, needed bailing out almost immediately. Letters to Nottingham in September 1703 drip with gratitude for cash advances to assist in ‘clearing the encumbrances upon myself and estate’. It has been well observed that political sympathy preceded this marriage alliance, and that there can be no question of Mostyn’s having enrolled as a parliamentary ‘client’ of Nottingham. On the other hand, family connexion and, more important, monetary obligation must at least have reinforced the effect of shared principles, and for some years Mostyn’s political course ran in close parallel with his father-in-law’s. At the beginning of the ensuing session he served as teller on 25 Nov. 1703 for leave to bring in the occasional conformity bill. He told again on 9 Dec. for an adjournment motion, and on 26 Jan. 1704 reported on a private bill concerning the estate of Thomas Legh I*. At about this time Mostyn appeared as a member of a ‘secret committee’ of Tory back-benchers, the existence of which is disclosed in a document in the papers of Sir William Trumbull* and which may have originated in the Commons’ defence of Nottingham over the Scotch Plot. In March Nottingham included Mostyn upon a list of likely supporters in the proceedings upon this matter. Whatever its motivation, the unity of this ‘steering group’ was broken by the Tack, an issue in which Mostyn followed Nottingham and not former friends like Henry St. John II* and Simon Harcourt I*. Forecast twice as a probable supporter of the Tack, he was not even lobbied by the Harleyites and in the vital division on 28 Nov. 1704 voted with the other High Churchmen. Later in that session he was nominated, on 14 Dec., to give the thanks of the Commons to the Duke of Marlborough (an awkward prospect in view of his stance in 1702 against the royal grant). But his energies were mainly bent towards securing the passage of a bill he had himself presented on 29 Nov. on behalf of the button-makers of Cheshire and Staffordshire, to stop the manufacture of buttons from raw materials other than leather, in particular the imported beans and berries that were the raw materials of a rival London-based industry. A teller three times in divisions arising from the bill, he was probably designated chairman of the select committee to which it was referred (being named first in the list of the committee), but was never given the opportunity to report. More successfully, in February he reported and carried to the Lords a private bill concerning a Cheshire family.7

Mostyn, described with other Tackers in a parliamentary list of 1705 as ‘True Church’, suffered for his hatred of occasional conformity, first by being deprived in March 1705 of the constableship of Flint Castle, and then by losing his parliamentary status as a knight of the shire, when he and the other outgoing Tory, Sir George Warburton, 3rd Bt.*, were defeated by two Whigs in Cheshire. Possibly the failure of the button bill had damaged his prestige, but his vote for the Tack seems the more probable reason for his downfall, the ‘Church in danger’ being the principal issue at the poll. It was to be Mostyn’s last experience of Cheshire elections; he fell back on the Flint Boroughs constituency, and thereafter confined his parliamentary candidatures to his ancestral counties. He spoke for William Bromley II* and voted against the Court candidate in the division on the Speakership, 25 Oct. 1705. In all probability he was the ‘Sir Roger Puleston’ named in the Journals as a teller on 24 Nov. on the Tory side in the St. Albans election dispute, and on 8 Dec. he spoke in the ‘Church in danger’ debate, conceding that he would be prepared to ‘condemn the practice’ of libelling crown and ministry, but refusing to vote for the Lords’ resolution, on the grounds that ‘the bill is sufficient to garble corporations’. This was the first of several recorded speeches during this session. At the second reading of the regency bill, which he had earlier told against, he weighed into the controversy arising from Charles Caesar’s* innuendoes against Lord Treasurer Godolphin (Sidney†). Evidently defending Caesar, he pointed out that it was on Godolphin’s ‘advice [that] the Qu[een] passed the [Scottish] Act of Security’. Further speeches came on 19 Jan. 1706, on the composition of the regency, and two days later, on the ‘whimsical clause’. Support for this provision was subsequently expressed in two tellerships: on 4 Feb., against one of the Lords’ amendments; and on 18 Feb., against a further Whig amendment in the Commons to one of the Lords’ amendments. He had also acted as a teller on 22 Jan. against John Pedley* in the Huntingdon election; and did so again on 8 Mar., on the opposition side, against the condemnation of the Letter from Sir Rowland Gwynne*. For the remainder of the Parliament he was notably less active, though he did move on 13 Dec. 1706 an additional clause to the union bill ‘in favour of the Convocation of the clergy as part of the constitution’, a proposal described by one commentator as ‘ludicrous’. Locally, he used his position as bailiff of Flint to mount a rearguard action against his successor as constable, Sir John Trevor*, holding his own court at the castle, and procured a writ of mandamus to prevent Trevor from being sworn in, though the costs of these actions occasioned financial difficulties for Mostyn. Twice in parliamentary lists of early 1708 he was classed as a Tory. In the general election of that year his turn came again to be knight of the shire for Flint. He assisted Hanmer in ‘whipping in’ north Wales Tories at the start of the new Parliament but made little impact himself on its proceedings. As early as December 1708 he was bemoaning that the manner in which the Commons was being managed meant that ‘I have no reason to stay in town but upon my own business’, and he was not included upon either of this Parliament’s printed division lists.8

By contrast, the 1710 Parliament saw Mostyn as once again among the more active Tory back-benchers. He was nominated on 5 Dec. 1710 to prepare a bill to prevent bribery and corruption at elections, and on 20 Dec. told against an amendment to the land tax bill. As one of the ‘worthy patriots’, and a member of the October Club, he took a leading role in the exposure of maladministration on the part of the old ministers, reporting on 13 Feb. and 23 Apr. from a committee of inquiry into false musters and payments to the guards and the Royal Hospital. On 3 May he told for an extra clause to the bill for the relief of the creditors and proprietors of the Mines Adventurers’ Company. By the end of the session he was receiving overtures from the Court, and after rejecting the offer of a seat at the Board of Trade accepted in July 1711 the paymastership of the marines. This commitment kept him from following Nottingham into opposition in December 1711 over the peace. Instead, he became for a time one of the Court’s agents inside the October Club, in which Boyer marked him as one of the leading lights. On 24 May 1712 he acted as a teller against an amendment to a resolution concerning his predecessor as marines paymaster. His solicitations on behalf of his youngest brother to be appointed receiver of the land tax for Cheshire and north Wales in the autumn of 1712 seem to have been unsuccessful, and while it is unlikely that this particular incident caused him to be alienated from the ministry, his loyalty did in fact crack in June 1713 when he voted on the 18th as a ‘whimsical’ against the French commerce bill. Whether Nottingham’s influence was brought to bear, or that of his long-time friend and Flintshire associate Hanmer, cannot be discovered. It is equally possible that he may have felt the same local pressures as did Peter Shakerley* at Chester. Little is known of his political conduct for the rest of Queen Anne’s reign. He failed to win Caernarvonshire in 1713 in circumstances which aroused the anger of Nottingham against ‘the contrivances of one who has been obliging my family everywhere’, and turned again to Flint Boroughs. The Worsley list classed him as a Tory who would often vote with the Whigs, and in lists of the Members re-elected in 1715 he was described both as a Tory and as a Whig. By this time, however, he had slipped back under his father-in-law’s wing. It was through Nottingham’s intervention that he was eventually compensated for losing the marines paymastership in October 1714 with a tellership of the Exchequer, and that in November 1714 his candidate was given the vacant bishopric of St. Asaph. In turn, he was to go out with Nottingham in 1716, forfeiting every office and honour bar the recently reacquired constableship of Flint Castle, which he was able to pass on to his eldest son in 1728.9

Mostyn voted consistently against the government after 1716, but seems to have steered clear of Welsh Jacobite societies. In 1727 his son Thomas†, a Hanoverian Tory, forced the sheriff of Flintshire to proclaim George II, a service for which, presumably, Sir Roger was rewarded with the lord lieutenancy. But in 1738 Jacobite intelligence reported that the Duke of Marlborough, ‘when he was last summer at Sir Roger Mostyn’s’, found the first health after dinner was constantly ‘the Chevalier’. Mostyn died on 5 May 1739, and was buried at Llanrhos, Caernarvonshire.10

Ref Volumes: 1690-1715

Author: D. W. Hayton


  • 1. L. N. V. Mostyn and T. A. Glenn, Fam. of Mostyn, 155–6, 158–60; J. E. Griffith, Peds. Anglesey and Caern. Fams. 183; Add. 61119, f. 182; Luttrell, Brief Relation, v. 315; Studies in Social Hist. ed. Plumb, 157; Chirk Castle Accts. 1666–1753 ed. Myddelton, 297.
  • 2. Chirk Castle Accts. 297.
  • 3. Add. 36127, f. 161; 36128, f. 13; Cal. Treas. Bks. xvi. 314, 320; xvii. 286, 461; xix. 552; xxv. 433; L. Colley, In Defiance of Oligarchy, 188.
  • 4. Hearne Colls. vi. 45, 56, 66; viii. 21; xi. 58; Arch. Camb. ser. 1, iii. 245; ser. 3, iv. 346; v. 165, 167; vi. 13, 18, 179; Nichols, Lit. Hist. iii. 243–4, 247–51, 270; Cal. Treas. Bks. x. 1375; Mostyn and Glenn, 160; Atholl mss at Blair Atholl, 45/II/127, Ld. Hamilton to [Ld. Tullibardine], 14 Nov. 1701.
  • 5. Add. 28894, ff. 298, 300.
  • 6. HMC Cowper, iii. 12, 57; HMC Kenyon, 428; Norris Pprs. (Chetham Soc. ser. 1, ix), 102–3; O. Klopp, Corresp. de Leibniz avec L’Electrice Sophie, ii. 406–7.
  • 7. Add. 22852, ff. 73–76; 29588, ff. 149, 163; Atterbury Epistolary Corresp. iv. 384–5; Top. and Gen. iii. 46; Luttrell, v. 316; CSP Dom. 1702–3, p. 536; L. K. J. Glassey, Appt. JPs, 159; H. Horwitz, Revolution Politicks, 263–5; Studies in Social Hist. 157–8; R. Walcott, Pol. Early 18th Cent. 59, 210; HMC Downshire, i. 817; Speck thesis, 117; CJ, xiv. 429, 449, 492, 555.
  • 8. W. A. Speck, Tory and Whig, 16; HMC Portland, iv. 189; John Rylands Univ. Lib. Manchester, Legh of Lyme mss corresp. Mostyn to Warburton, 25 Sept. [1705]; Cobbett, Parlty. Hist. vi. 450; Cam. Misc. xxiii. 49, 52, 75, 81; Chandler, iv. 57; Cal. Treas. Bks. xxi. 173; NLW, Chirk Castle mss E995, Mostyn to Sir Richard Myddleton, 3rd Bt.*, 24 Oct. 1708; Leics. RO, Finch mss box 4950 bdle. 22, Mostyn to Nottingham, 11 Oct. 1707; bdle. 23, same to [same], 16 Dec. 1708.
  • 9. SRO, Mar and Kellie mss GD124/15/1020/12, Sir James Dunbar, 1st Bt.*, to Ld. Grange (Hon. James Erskine†), 17 Feb. 1711; Add. 70256, Ld. Rivers (Richard Savage*) to Ld. Oxford (Robert Harley), 8 June 1711; 70214, William Bromley II to same, 1 Sept. 1712; Northants. RO, Isham mss IC 2216, John to Sir Justinian Isham, 4th Bt.*, 12 June 1711; HMC Downshire, i. 894; Bull. IHR, xxiii. 227; G. Holmes, Pol. in Age of Anne, 281; Jnl. Brit. Studies, vi. 53; Boyer, Pol. State, iii. 120; Devonshire mss at Chatsworth House, Finch-Halifax pprs. box 5, bdle. 13, Nottingham to Ld. Guernsey (Hon. Heneage Finch I*), 26 Sept. 1713; Horwitz, 246–7; Lady Cowper Diary, 29–30; HMC Portland, vii. 205, 207, 209.
  • 10. Colley, 36–37; RA, Stuart mss 206/106, Thomas Carte to Col. O’Brien, 4 May 1738; Griffith, 183; Mostyn and Glenn, 161.