Biddulph made a fortune in Bengal, contracting in bullocks as a private merchant.
Biddulph acted with the Foxite Whigs in Parliament, making his debut as a critic of the cavalry bill in November 1796 and acting as teller against it on 13 Dec. On 20 Dec. he criticized the East India Company accounts and on the 22nd unsuccessfully moved for information on the new code of judicature for India. On 26 May 1797 he voted for Grey’s reform motion, having attended the Crown and Anchor meeting in its favour, but he did not agree with the Whig secession. He was critical of the tax on farm horses, 30 June. He opposed Pitt’s assessed taxes, 4 Jan. 1798, and characterized the land tax redemption bill as an unconstitutional fraud, 30 May. He voted against the Irish union, 7 Feb. 1799, and continued his silent opposition to Pitt’s war policy. He complained of the tax burden on farmers, 26 May 1800, and supported the London bread bill, 16 June and 5 July. On 14 Apr. 1801 he voted against the suspension of habeas corpus and on 5 June against the indemnification of government informers since 1793.
Biddulph was defeated in the county election of 1802, when Sir George Cornewall was reinstated with the help of the second votes of Biddulph’s opponents. The Times alleged on 21 July:
Mr Biddulph, who has constantly voted with opposition on every question during the war, and considered the Corresponding Societies as very harmless institutions, is suddenly left in a most disgraceful minority, even after his re-election was considered secure. A proof how little his politics have been esteemed in that county.
Biddulph’s friends went on to unseat Cornewall, but in circumstances that prevented his attempting to resume the seat and he was out of Parliament until 1806.
In 1798 Biddulph had contemplated a return visit to India: Lord Cornwallis hoped that there would be a ‘truce to his politics’.
Myddelton Biddulph returned to Westminster as a man of business, with a sense of mission about securing public economy. On 24 Dec. 1806 he attempted to cancel the salary of the chairman of ways and means, without success because it was paid in retrospect. On 17 Jan. 1807 he seconded Johnstone’s motion against the army estimates. On 10 Feb. he secured a select committee of 21 to review public expenditure and, if possible, lower it by reducing sinecures, though ministers doubted if there was much scope remaining for this. He underlined his independence of party when on 13 Feb. he spoke for the minority on the Hampshire election petition and on 27 Feb. he defended the Westminster petition on behalf of James Paull. He nevertheless voted for Brand’s motion following the dismissal of the Grenville ministry, 9 Apr. 1807.
Myddelton Biddulph clung to his seat in 1807 and continued his independent opposition line. He voted against the address, 26 June, and for Whitbread’s censure motion, 6 July. A week before, he had upheld the work of the finance committee he had initiated and regularly attended. It had, to quote Lady Holland, ‘struck a general alarm into sinecure placemen and peculators, as it is known to be composed of very active, ardently zealous reformers’.
He voted against ministers throughout on the Scheldt inquiry, January-March 1810, and against committing Burdett to the Tower, 5 Apr. The Whigs were ‘hopeful’ of his support. He could not be rallied to an extra-parliamentary meeting in 1811 to promote constitutional reform, though he had voted for Brand’s motion on 21 May 1810. He regularly voted for Bankes’s efforts to reduce sinecures between 1810 and 1812. He acted with opposition on the Regency and on 9 July 1811 voted against the bank-note bill. He voted for Whitbread’s critical motion on the deterioration of relations with the United States, 13 Feb., and for Turton’s censure motion, 27 Feb., as well as for a review of the orders in council, 3 Mar. 1812. He was in the minorities against John McMahon’s appointment, 14 Apr., and for Catholic relief, 24 Apr. He was in the majority for a stronger administration, 21 May. His last known speech was hostile to the leather tax, 26 June 1812.
Myddelton Biddulph had since 1811 been faced with a contest for Denbigh, owing to his quarrel with his wife’s brother-in-law. After an acrimonious contest, he was defeated by an anti-Catholic ministerialist. He died 30 Aug. 1814, leaving his heir with an income of £70,000.
