In 1721 he succeeded to half of the enormous estates of his uncle, Sir Charles Duncombe.
[2] He vacated his seat in 1747 when he was raised to the peerage as Lord Feversham, Baron of Downton, in the County of Wilts.
She died in 1755 and was buried in Downton, Wiltshire with a memorial sculpted by Peter Scheemakers.
They had one daughter, Anne Duncombe (d. 1829), who married her step-brother Jacob Pleydell-Bouverie, 2nd Earl of Radnor.
Lady Feversham married as her second husband William de Bouverie, 1st Earl of Radnor.