THELLUSSON, Peter Isaac (1761-1808), of Rendlesham House, nr. Woodbridge, Suff.

Published in The History of Parliament: the House of Commons 1790-1820, ed. R. Thorne, 1986
Available from Boydell and Brewer



17 Jan. 1795 - 1796
1796 - 1802
1802 - 1806
1807 - 16 Sept. 1808

Family and Education

b. 13 Oct. 1761, 1st s. of Peter Thellusson, and bro. of Charles Thellusson* and George Woodford Thellusson*. educ. Harrow 1774. m. 14 June 1783, Elizabeth Eleanor, da. of John Cornwall, Russia merchant, of Hendon, Mdx., 6s. 1da. suc. fa. 1797; cr. Baron Rendlesham [I] 1 Feb. 1806.

Offices Held

Dir. Bank of England 1787-1806.

Lt.-col. commdt. Rendlesham vols. 1798, capt. commdt. 1803.


The Thellussons were originally Huguenots who fled from France to Geneva after the Edict of Nantes. Issac de Thellusson (1690-1770) became Genevan ambassador at Paris where his second son, George, founded a banking house, while his third son, Peter, came to England and was naturalized in 1762. Stories later circulated that he had been taken into partnership (or, in some versions, employed as a clerk) by John de Grenier Fonblanque, father of John Fonblanque*, who had gone into business with his brother Anthony at Water Lane, London. ‘Fonblanque dying’, so Farington heard, ‘left his share of the business to be carried on for the benefit of his widow, in conjunction with Thellusson, but the latter managed to get the whole concern into his own hands.’ In 1805 Thomas Grenville referred to the late Peter Thellusson as ‘a Swiss and a banker’s clerk’.1

While he certainly had an early connexion with the Fonblanques, the truth of these allegations is open to doubt. The firm of John and Anthony Fonblanque and Thellusson was in existence by 1763 and continued as such until about 1769, when it became Fonblanque & Co., before disappearing from the directories some time after 1781. Peter Thellusson was first listed as a merchant on his own account, with premises at 15 Philpot Lane, in 1770. The business later became known as Peter Thellusson & Co. (1772), Thellusson, Cossant & Co. (1780), and Peter Thellusson, Sons & Co. (1791). Thellusson’s son claimed in 1796 that his father had ‘settled with a handsome fortune in this country’ and increased it ‘by his industry and his abilities’.2 Whatever his methods, Peter Thellusson, who acted as agent for leading European commercial houses, traded to the West Indies and acquired plantations in Grenada and Montserrat, prospered handsomely. He bought the Brodsworth estate and built a house at Plaistow in Kent, retiring from trade in 1790, when his sons took over the business, to be known as Thellusson Brothers, which moved from Philpot Lane to Little Eastcheap in 1797. They were said to have made ‘great sums’ from remittances deposited by Frenchmen who subsequently perished on the guillotine and their profits in 1795 were put at £83,000; they also contracted for the public loan from 1793; but Farington wrote in 1803 that they could not rival the house of Baring in reputation and success:

The Thellussons might have been of more consideration, but they have been losers by speculating, and have not so conducted themselves as to be esteemed: Their bond is looked upon to be of more value than their word.3

Peter Thellusson died in 1797, leaving one of the most spectacularly vindictive wills in British history. He left Plaistow to his widow and the Philpot Lane premises in trust for his three sons (provided they remained active partners for six years) together with legacies of about £100,000 to members of the family. The remainder of his real and personal property, including Brodsworth and valued at over £600,000, he assigned to trustees to be invested in land and left to accumulate during the lives of all his sons, grandsons and great-grandsons living at the time of his death, at the end of which period the fund was to be divided between the eldest male living descendants of his sons in tail male. In the absence of an heir, it was to be applied towards payment of the national debt. Thellusson deemed the provision he had made for his sons (£7,600 each, in addition to earlier gifts of £15,400, plus the business) ‘sufficient to procure them comforts’ and counselled them to ‘avoid ostentation, vanity and pompous show’, advice which Peter Isaac, who became renowned for his frequent and lavish entertainments, conspicuously ignored. The family challenged the validity of the will, but it was upheld in Chancery in 1799 and again in the Lords in 1805. In 1800 an Act was passed prohibiting similar schemes of bequest. As there were no great-grandchildren alive in 1797 the trust was in practice limited to the life of two generations and ended with the death of the last surviving grandson in 1856. After further litigation the estate was divided between the two male representatives of Peter Isaac and Charles Thellusson, but owing to mismanagement and legal costs it realized a comparatively modest amount.4

Peter Isaac Thellusson was returned on a vacancy for Lord Egremont’s borough of Midhurst in January 1795, supported Pitt and acquired a wholly deserved reputation as a peerage-hunter. He spoke in defence of his younger brother’s part in the concoction of a memorial of claimants on property confiscated in Martinique, 4 May and 2 June 1795, when he also voted for Foster Barham’s motion criticizing the conduct of Grey and Jervis on the island. At the general election of 1796 he came in for Malmesbury as a paying guest on the Wilkins interest. On 11 Nov. 1796 his brother George’s expensively won election for Southwark was declared void. The following day Peter asked Windham to inform Pitt that although the family would remain attached to government in any event, they required a ‘reasonable assurance’ of a peerage for his father or himself if they were to contest the Southwark by-election, involving as it would ‘exertions and enormous expenses’ which went ‘beyond the duty imposed upon us towards the state and must be looked upon as a bold and volunteering spirit in its defence’. Political services apart, he went on, the family’s pretensions stood comparison with those of other ‘mercantile men’ ennobled by Pitt, his father was no longer involved in trade and his own continuance in it was ‘uncertain’: ‘I am daily vesting my fortune in land, and certainly my eldest son will not be brought up to trade’.5 In passing the buck to Pitt, Windham was unable to give decisive advice:

My goodwill to the object is only conditional: if such things are to be, if this door now as I think unhappily opened, is still to let in persons of the description in question, there is then no conscience in aiding one person with equal pretensions instead of another. But I lament that this conditional goodwill should ever be called forth ... I drop this child at your door. You will judge whether I should take it back again, without confessing what I have done, or whether you will allow it to be admitted, taking such measures to prevent its being fixed upon you too conclusively, as you shall think proper.6

It seems likely that Thellusson received some encouragement, for his brother stood successfully for Southwark at the by-election. His last known speech in the House was in support of George’s motion, 12 Dec. 1796, for postponement of the appointment of the committee to investigate his opponent’s petition, on which he was later unseated.

Thellusson, who bought the Rendlesham estate for £51,400 and invested in East India Company stock, voted with the majority on the loyalty loan, 1 June 1797, having subscribed £10,000 in his own and £50,000 in the firm’s name. He was among the merchants who met to condemn the mutiny in the fleet, 7 June 1797.7 He did not initially oppose the Addington ministry, though, probably with an eye to the reversionary interest, he voted for inquiry into the Prince of Wales’s claims to duchy of Cornwall revenues, 31 Mar. 1802. At the subsequent general election he was returned for Castle Rising as a paying guest of the Prince’s friend Lord Cholmondeley, and also unsuccessfully contested Okehampton. It is not clear whether Peter or Charles was the Thellusson dismissed by Lord Redesdale as ‘a shuffling man’, who, ‘having been counted on by government’, divided with opposition against the proposal to adjourn pending confirmation of the renewal of war, 6 May. 1803.8 He followed Pitt into the combined onslaught on Addington in 1804, when he voted in the divisions of 15 Mar., 13, 16, 23 and 25 Apr., and supported his second ministry, voting against the censure of Melville, 8 Apr. 1805.

In July 1805 he asked Pitt to expedite an earlier promise to recommend him for an Irish peerage by invoking the power vested in the crown by the Act of Union to create one new peer when three Irish titles had become extinct, as they had, so Thellusson claimed, with the deaths of Lords Mountrath, Bateman and Ross in 1802. While he was mistaken in this assertion, Mountrath’s barony having passed by special remainder to Charles Henry Coote*, the death in 1804 of Lord Holmes had in fact produced the required three extinctions. Pitt was clearly ready to concede the point, but there was a delay, which was agitating Thellusson mightily by October 1805, while the legal position was fully investigated. Lords Camden and Castlereagh were understood to have reservations about the award, and when it was finally approved in November two more of Pitt’s colleagues, Lord Bathurst and Spencer Perceval, begged him to think again, Perceval going so far as to say that the grant would damage Pitt more severely than any blow which his domestic or foreign enemies could inflict.9 Even though the patent had been made out, Pitt’s death and the change of ministry caused further delay in the formal announcement and Thellusson, who was frantic with worry, became a laughing-stock, having ‘had all his carriages painted, and plates engraved with coronets’: his title, joked the wits, was one of the oldest in existence, because he was ‘a peer before the creation’. The peerage, described by Lord Sidmouth as ‘an outrage to common decency’ and by Speaker Abbot as a source of ‘great offence’ to the Irish nobility and gentry, was officially conferred on Thellusson on 1 Feb. 1806. Lord Melville was alarmed by the inevitable rumours that Pitt had been heavily in debt to Thellusson, but Huskisson assured him that Pitt had not owed him a shilling and had ‘conferred a favour upon him only as the means of strengthening the King’s government. He was in no habits with him, and had no wish to be, considering him an unpleasant and shabby fellow, which he unquestionably is.’10

‘Lord Rendle-sham’, as he was widely known, opposed the ‘Talents’, voting against the repeal of the Additional Force Act, 30 Apr., and the American intercourse bill, 17 June 1806, and failed to find a seat at the ensuing general election. In 1807 he was unsuccessful at Seaford, but was returned for Bossiney on the Mount Edgcumbe interest as a friend of the Portland ministry, which he supported until his death.11

In 1806 Farington wrote that Rendlesham did ‘not reside more than two months in the year in London, being much more inclined to a country residence’. He had ‘lately’ withdrawn from the family business when he made his will in April 1806, his place having been taken by his second son George, who was to be killed in action at Vittoria in 1813. In 1807 Farington heard that ‘it is doubted whether Lord Rendlesham ... has a large fortune’, but the terms of his will indicated considerable personal wealth and he was said to have left £400,000 at his death, 16 Sept. 1808.12

Ref Volumes: 1790-1820

Author: David R. Fisher


  • 1. D. C. A. Agnew, Protestant Exiles (1886), ii. 381; E. B. de Fonblanque, Life of Albany Fonblanque (1874); Farington, ii. 127; HMC Fortescue, vii. 315.
  • 2. PRO 30/8/182, f. 176.
  • 3. Farington, ii. 111, 127; iv. 169; v. 234.
  • 4. Gent. Mag. (1797), ii. 624, 708; (1798), ii. 1082; (1832), ii. 177; J. Hunter, Deanery of Doncaster, i. 317-18; Annual Reg. (1859), Chron. p. 332; N. and Q. (ser. 8), xii. 183, 233, 489; (ser. 9), i. 17, 97; viii. 53.
  • 5. PRO 30/8/182, ff. 174-7.
  • 6. PRO 30/8/330, f. 328.
  • 7. W. A. Copinger, Suff. Manors, iv. 319; The Times, 8 June 1797.
  • 8. Add. 35714, f. 81; 35717, f. 90.
  • 9. PRO 30/8/112, f. 71; 182, ff. 170, 172; 328, f. 259; E. Suff. RO, Tomline mss, Rose to bp. of Lincoln, 15 July 1805; PRO, Dacres Adams mss 6/127, 159.
  • 10. Dacres Adams mss 7/9; D. M. Stuart, Dearest Bess, 135; Sidmouth mss, Sidmouth to J. H. Addington, 7 Jan. 1806; Colchester, ii. 38; Add. 38737, f. 123; SRO GD51/1/91.
  • 11. Colchester, ii. 38; J. Wilson, Biog. Index (1808), 75.
  • 12. Farington, iii. 248; iv. 169; v. 128; PCC 920 Ely.