Pelham succeeded his father at Lewes, which he represented as a Whig on the family interest for 36 years. At George I’s accession he obtained a place of £500 a year, which he exchanged for one of £1,000 a year, no doubt through the influence of his kinsman and patron, the Duke of Newcastle, when the board of Trade was reconstituted after the split in the Whig party in 1717. On 23 Mar. 1720 he made his first and last reported speech, against Walpole’s motion for fixing the rate of conversion of government securities into South Sea stock. An occasional rather than a constant attender at board of Trade meetings, but a regular voter for the Government, he nearly lost his seat at the general election of 1734. ‘Old Tom Pelham’, Newcastle wrote to his wife during a pre-election visit to Sussex in the summer of 1733, ‘is as unpopular as possible and has personally disobliged the whole town’.
the loss of it must be imputed to Mr. Pelham’s inactivity, who will not stir for all the frequent and earnest solicitations of myself and all his friends. He knows little of his affairs; nothing but by report, though he has opportunities every hour of the day to satisfy himself of the truth. He has not been round the town since he went with your Grace, nor I believe asked a single man for his vote; and I am fairly persuaded that half the votes that have been lost have been lost by this unpardonable negligence.
A few days later Hay wrote that his father-in-law had been so upset at learning of these defections that he had taken to his bed for a week.