Stopford, the son of a courtier, was awarded a commission in the Coldstream Guards by King George III ‘as soon as he was of age to have one’. On 13 Dec. 1786 his mother wrote to Pitt, without her husband’s knowledge, pointing out that her son’s income as an ensign was inadequate and asking if he might have a place in the customs. She added: ‘My ambition is, and I own my ambition runs very high for this son, that he should get into Parliament, in time I hope it will be accomplished, and if he is my son, Mr Pitt will have no firmer friend’. In August 1787 the Duke of York proposed Stopford to the King for his household, but nothing came of it. His mother’s uncle the 1st Earl of Ailesbury brought him in for Bedwyn on a vacancy in 1790, his father being then Ailesbury’s Member for Marlborough. Like him, he gave a courtier’s support to Pitt’s administration. He was listed hostile to repeal of the Test Act in Scotland in April 1791; early in 1792 he declined a pair with the champion of that repeal, Sir Gilbert Elliot. In 1793 he succeeded his father as treasurer of the Household and, as such, regularly delivered royal messages to the House, but had nothing to say in debate.
Stopford’s father-in-law, the Duke of Buccleuch, returned him for Linlithgow Burghs in 1796, despite doubts as to his eligibility, his father having just been made a British peer. At the next election the duke was again his patron, when after a delay he was substituted for Charles Hope in Dumfries Burghs. Henry Dundas, who was behind the manoeuvre, had dissuaded the duke from substituting Stopford for his son Lord Dalkeith at Ludgershall.