He was an active supporter of the Royal Agricultural Society of England from its commencement in 1838, and served as president in 1846, 1856, and 1862.
He was a considerable breeder of Devon cattle and of improved Alderney cows.
[1] In 1823 Portman was elected to Parliament as a Whig for Dorsetshire,[1] a seat he held until 1832, and then represented the newly created constituency of Marylebone from 12 December 1832 to March 1833.
[1] Another son, Edwin Berkeley Portman, became Member of Parliament for North Devon.
[1] He was a descendant of Sir William Portman, Lord Chief Justice of England between 1555 and 1557.