Colonel Saunderson was the third but eldest surviving son of Colonel Alexander Saunderson, M.P, of Castle Saunderson, Belturbet, Co. Cavan, and the Honourable Sarah Juliana Maxwell, eldest daughter of the sixth Lord Farnham of Cavan.
Born in 1837, he was educated on the Continent. He married the Honourable Helena de Moleyns sister of Lord Ventry, who was the founder of the Women's Orange Association.
Colonel Saunderson's military title was derived from the Cavan Militia, in which he served as a subaltern, captain and field officer for over 30 years. His first experience of practical politics dates from the year of his marriage in 1865, when he was returned as the Liberal representative for Co. Cavan, in conjunction with the Hon. Hugh Annesley, of Annesborough, Co. Down. On winning this election he replaced his uncle, afterwards the ninth Lord Farnham who had sat from 1857.
In the 1879 general election the Home Rule candidates Joseph Biggar and Mr. Fay swept County Cavan and nothing was heard of the Colonel until 1885. In that year he was selected as the candidate for North Armagh, and being elected on the anti-Home Rule ticket, held the seat until his death.
During his political career he attended several large anti Home Rule Rallies in Lurgan Town Hall. But while his fame was in the political field, he also made a considerable contribution to the strengthening of the Orange Institution, and was elected Grand Master of Belfast in 1901.