being elected for Buckingham in the conservative interest. In the session of 1829 he made some strong speeches condemning the pauperising influence of the poor laws then prevalent, and giving instances of the degradation that sprang from the existing mode of paying the wages of labourers, who were often put up to auction and their labour sold for two shillings a week. In 1833 he was appointed chairman of a select committee to inquire into the bribery employed at the Stafford election, and he succeeded in carrying a disfranchising bill in the face of much opposition. When Peel came into office for a brief period in 1834 Fremantle was appointed one of the secretaries of the treasury, an office which he resumed for three years in Peel's administration of 1841. In 1844 he became secretary at war, and in 1845-6 chief secretary for Ireland, in which capacity he defended the Maynooth College bill. In January 1846 he introduced the Irish public works bill, and he procured the expenditure of 50,000l. upon the construction of small piers and harbours, with the view of extending the fisheries of Ireland. Both measures were well adapted to the immediate needs of the country, were drawn and explained by Fremantle with signal ability, and were successfully piloted by him through the shoals of parliamentary debate.
In 1846 Fremantle resigned his seat at Buckingham and was appointed deputy-chairman of the board of customs. He was subsequently appointed chairman of this department, a post which he held until 1873. On the accession of Lord Beaconsfield to power in 1874 he was raised to the peerage (2 March). The first title that he chose was that of Lord Chiltern, but this was discarded for the name of the hundred in which his seat of Swanbourne was situated, and he became Baron Cottesloe of Swanbourne. Though a frequent attendant in the upper house he spoke but little. In 1875 he took a considerable interest in Lord Lyttelton's bill for the increase of the episcopate, and on the third reading he moved an amendment limiting its operation to five places—Guildford or Southwark (diocese of Winchester), Bodmin or Truro (Exeter), Southwell or Nottingham (Lincoln), St. Albans (Rochester), and Liverpool (Chester). He disclaimed hostility to the principle of the bill, but thought it unwise to send to the lower house a measure which provided for an indefinite extension of the episcopate; on the recommendation of the government, however, he consented not to press his amendment. Four years later he moved for a statement of the trade of the United Kingdom with the United States for the years 1873-8, adducing a formidable array of statistics to prove that the balance of trade between this country and America had been unfavourable to England, and that the exports were falling off in an alarming manner. The return was granted and prepared, and excited much controversy and comment in the press. In 1880 Cottesloe was a member of the select committee of the lords on intemperance, while among other subjects in which he was warmly interested were measures for increasing the safety of railway travelling and the deceased wife's sister's bill this last forming one of the ‘liberal shadows’ upon his conservatism which some of his friends deplored. As a county magnate, churchman, and patron of the Church Missionary Society he was extremely popular in Buckinghamshire, and in later years venerated as the father of the House of Lords and patriarch of Buckinghamshire society. On completing his ninetieth year he celebrated the event by inviting to receive the communion with him at St. Michael's, Chester Square, a number of his oldest friends, of whom about sixty responded, including the Brodricks, Julian Halls, Nugents, and Yerneys, and also his neighbour Sir Harry Verney, himself then eighty-seven years old. Cottesloe's children and grandchildren presented him upon this occasion with a cabinet in which to keep the decorations gained by his father, who commanded a ship at Trafalgar, and his uncle, Sir William Fremantle, an intimate friend of George III. His declining year's were clouded by the sad death of his wife in 1875, the result of her swallowing a lotion in mistake for a draught, and that of a granddaughter kicked to death in her father's sight by a runaway pony.
Cottesloe died at Swanbourne on 3 Dec. 1890, and was buried there on 9 Dec. He was then nearly ninety-three. He had attended the House of Commons on budget night from 1827 to 1889 without a break, nineteen times as a member of parliament, twenty-eight times as chairman of customs, and the remainder from the news gallery. He married, 24 Nov. 1824, Louisa Elizabeth (d. 17 Aug. 1875), eldest daughter of Field-marshal Sir George Nugent, bart., by whom he left issue three daughters and four sons: Thomas Francis Fremantle, second baron Cottesloe; the Very Rev. William Henry Fremantle, dean of Ripon; Sir Charles William Fremantle, K.C.B., comptroller of the Mint; and Admiral Sir Edmund Robert Fremantle, K.C.B., C.M.G.
[Burke's Peerage; G. E. C[okayne]'s Complete Peerage; Gent. Mag. 1797 i. 251, 1798 i.