In Parliament he was the member of a group including Henry Chaplin, Albert Pell and Clare Sewell Read, that supported farming interests, and was chairman of the Agricultural Business Committee.

[3] In 1874, Lopes was appointed Civil Lord of the Admiralty in the second Conservative administration of Benjamin Disraeli, a post he held until the government fell in 1880.

Bad health forced him to decline the post of Financial Secretary to the Treasury in 1877.

Lopes married firstly Bertha, daughter of John Yarde-Buller, 1st Baron Churston.

After her death in 1872, he married secondly Louisa, daughter of Sir Robert Newman, 1st Baronet.