In 1864, Seely was the Deputy Lieutenant for Lincolnshire, when he played host to the Italian revolutionary Giuseppe Garibaldi, when Garibaldi visited 26 Prince's Gate Hyde Park, his house in London and Seely's estate at Brook House on the Isle of Wight.
Seely made his fortune in the Industrial Revolution through milling, agricultural machinery and coal mining.
[4] He later diversified his fortune into acquiring coal mines and property: in 1883 he owned 9,264 acres on the Isle of Wight,[5] 2,929 in Worcestershire and 394 in Bedfordshire.
[citation needed] Five other members of his family became Members of Parliament during the 19th, 20th and 21st centuries: Additionally, his great-grandson David Peter Seely, 4th Baron Mottistone, who was baptised with Winston Churchill and the then Prince of Wales (subsequently Edward VIII) as his godparents, was the Deputy Lieutenant for Lincolnshire, Lord Lieutenant of the Isle of Wight and its last Governor.
His youngest sister Jane Anne Seely married (1882) Henry George Gore-Browne who received the Victoria Cross during the Indian Mutiny in 1857.