A young baronet who was more attentive to his sporting interests than to his parliamentary duties, Mordaunt was the last of six successive generations of his family to represent Warwickshire, all of whom, with the exception of his grandfather, were Tories.
The constituency of South Warwickshire, for which Mordaunt was returned unopposed at the 1859 general election, had long been controlled by a handful of Conservative gentry and noble families, whose nominees were generally silent and lax attenders at Westminster. Mordaunt proved to be no exception to this pattern, but unfortunately for him, he was elected at a time when the long dormant local Liberal party and the Radical Birmingham press were starting to scrutinise and publicise this state of affairs. In 1865, the Birmingham Daily Post revealed that Mordaunt had voted in 6 out of 222 divisions in 1862, 14 out of 188 divisions in 1863, and 22 in 156 divisions in 1864.
At the 1865 general election, when he and his Conservative colleague faced a Liberal challenge, Mordaunt invoked his family’s tradition of parliamentary service and responded to criticism of his own performance by claiming that ’more of my time during the last session has been spent looking after your interests in Warwickshire than in the House of Commons’. He had gone to Parliament as a Conservative supporter and had fulfilled that pledge, as the duty of that party was not to pass measures, but to maintain ’a bold front and a strong opposition, which have prevented measures from passing into law which, if passed, would long ago have undermined the time-honoured institutions of our country’.
Mordaunt voted against the Liberal government’s 1866 reform bill and during the debates on the representation of the people bill the following year, voted to retain small boroughs and against increasing the representation of larger towns. He opposed Gladstone’s Irish church resolutions, 3 Apr. 1868, and retired at the general election in December that year.
In 1869 Mordaunt petitioned for divorce alleging adultery, which resulted in a sensational trial at which the Prince of Wales, widely thought to be perjuring himself, denied having ’any improper familiarity’ with Lady Mordaunt.
