Dundas vacated the Orkney seat which he occupied on his father’s interest at the 1820 dissolution, in accordance with the terms of the pact negotiated in 1818 with a coalition of smaller proprietors, and returned to his life as a country gentleman. He was not well enough to attend the election proceedings.
Although he was a staunch Whig, he was an infrequent attender and is not known to have uttered a word in debate. He voted against the grant to the Clarences, 16 Feb., and for Catholic relief, 6 Mar., information on the mutiny at Barrackpoor, 22 Mar., and postponement of the committee of supply, 30 Mar.1827. He divided for repeal of the Test Acts, 26 Feb., and Catholic claims, 12 May 1828. He voted in protest at delays in chancery, 24 Apr., for lowering the duty on corn imports, 29 Apr., against the use of public money for improving Buckingham House, 23 June, to reduce the salary of the lieutenant-general of the ordnance, 4 July, and against the grant for North American fortifications, 7 July 1828. He defaulted on a call of the House, 5 Mar., but was present to vote for Catholic emancipation, 6, 30 Mar.; he presented a hostile petition from Stromness, 24 Mar. 1829. He voted for the enfranchisement of Birmingham, Leeds and Manchester, 23 Feb., to transfer East Retford’s seats to Birmingham, 5 Mar., and for Lord John Russell’s parliamentary reform motion, 28 May 1830. He divided in condemnation of the filling of the vacancy of treasurer of the navy, 12 Mar. He may have presented a petition against the Garnkirk railway and Keppoch road bill, 19 Mar.; but his brother was probably the man listed as voting for inquiry into the management of crown lands, 30 Mar. He divided for Jewish emancipation, 5 Apr., 17 May. He voted for abolition of the Irish lord lieutenancy, 11 May, repeal of the Irish coal duties, 13 May, returns of privy councillors’ emoluments, 14 May, and abolition of the death penalty for forgery, 7 June. He voted for the critical motion on the civil government of Canada, 25 May, paired to reduce the grant for South American missions, 7 June, and probably voted to reduce the grant for Nova Scotia, 14 June 1830, when he did vote to reduce that for Prince Edward Island.
Dundas had lamented, 28 Feb. 1828: ‘At length, age overtakes me, the period is come when the fancy must close and the muse must be dumb’. He stepped down at the 1830 dissolution, but his retirement from public life was brief, as Sir James Graham*, first lord of the admiralty in the Grey administration, wrote to Lord Dundas, 20 Nov. 1830, seeking his assistance in ‘overcoming his brother’s reluctance to enter city life’ and become a lord of the admiralty. Graham suggested that his having a seat in the House would be useful, but, while he agreed to accept the position at the admiralty, Dundas refused to replace his brother Sir Robert at Richmond; he also declined to replace Lord Milton at Peterborough, not wishing to sit for an English seat.
Dundas died suddenly in the first week of October 1834. He had been viewing one of his farms before returning to Upleatham for dinner:
Shortly afterwards he retired to the water-closet, and the family, thinking he remained long, went to ascertain the cause, and found him sitting upon the seat, with his head reclining upon his knees, and in a state of insensibility. He was immediately removed to bed, and lingered on till 12 o’clock, when he expired, having never spoken from the first.The Times, 11 Oct. 1834.
He apparently had some responsibility for his niece, Emma Chaloner of Carshalton Park, Surrey, but left no will. Administration of his estate, which was sworn under £18,000, 3 Nov. 1834, was granted to his brother Sir Robert.