Barnard, heir to the great family wealth in landed property, was returned unopposed in 1812 for Durham where his father, a sometime Carlton House man who remained loyal to the Whigs after their abandonment by the Regent, had a powerful interest. He was elected to Brooks’s on 12 Mar. 1813 and his father, a member from 1788 until his resignation in 1802, rejoined the club in 1816.
Barnard was sometimes confused in the division lists with the Irish Member, James, Lord Bernard, but it is safe to assume, except in a few instances, that ministerial votes attributed to him were in fact cast by the other man. He voted in the opposition minorities on the vice-chancellor bill, 11 Feb.; the Regency, 23 Feb.; the East India Company’s monopoly, 14 June 1813, and East Indian pensions, 17 May 1814. He voted for Catholic relief, 2 Mar., 13 and 24 May 1813, and again 30 May 1815, 21 May 1816, 9 May 1817; and to censure the Speaker for his anti-Catholic prorogation speech, 22 Apr. 1814. He divided against government on the Bank restriction bill, 9 Mar.; the new taxes, 13 Mar.; the civil list, 14 Apr. and 8 May; Genoa, 27 Apr.; the income tax, 1 May, and the Regent’s expenditure, 31 May 1815, but was credited with a speech in favour of the corn bill, 10 Mar. As his younger brother voted against the measure, the speech may have been the work of Lord Bernard. Barnard was in the minorities on the resumption of hostilities, 7 and 28 Apr., 25 May, and voted against government on the Irish master of the rolls salary, 19 June, and the Duke of Cumberland’s establishment, 28 and 30 June, 3 July 1815. On 4 July he spoke in support of Marjoribanks’s independent motion for a vote of thanks to the Duke of York as commander-in-chief and two days later was ‘mad enough’, as one observer commented, to take a commission in the army, which vacated his seat.
His military career was largely nominal and in February 1816 he was returned on a vacancy for his father’s pocket borough. He was listed in the government majority on the army estimates, 6 Mar. 1816, when his brother voted in the minority, but this may have been Lord Bernard. He voted against government on Ireland, 26 Apr. 1816, and on a few questions of economy in May. He was ‘quartered close to Calais’ in January 1817, but came over in time to vote against the address on the 29th.
At the general election of 1818 he was returned unopposed for Tregony on his father’s interest. He signed the requisition calling on Tierney to take the Whig leadership in the Commons, and voted with him on Bank restriction, 2 Feb. 1819; Admiralty economies, 18 Mar.; Scottish burgh reform, 1 Apr. and 6 May; his censure motion, 18 May; the foreign enlistment bill, 3, 10 and 21 June; the public finances, 7 June, and the excise duties, 25 June. He was named as one of eight Members who voted with the ministerial majority in the first division on the question of Wyndham Quin’s alleged electoral corruption, 29 Mar., but with the minority in the second, ‘because they were desirous that the resolution which stated the circumstances of extenuation should precede the resolution of censure, and excuse the House for not proceeding to expulsion’.