His mother was Anna Maria Hunt, heiress of Lanhydrock, great-niece of Henry Robartes, 3rd Earl of Radnor and 4th Baron Robartes (which titles became extinct in 1757; see the Earl of Radnor 1679 creation for more information).
He commissioned the architect George Gilbert Scott to renovate Lanhydrock House but in 1881 it was badly damaged by a fire in which his wife died of smoke inhalation.
[1] Robartes was returned to Parliament for Cornwall East in 1847, a seat he held until 1868.
Lord Robartes died at 1 Dean Street, Park Lane, London on 9 March 1882, aged 73.
[2] He had married in 1839 Juliana Pole-Carew (1812–1881) of Antony House and had one son Thomas Agar-Robartes, 6th Viscount Clifden, who succeeded him in the barony and to Lanhydrock.