Son of Sir Charles Hay Seton, 7th Baronet of Abercorn and Caroline Hodges, he was born on the 31st of January, 1836.  His uncle, Sir Henry John Seton 6th Baronet, was a Captain in the Army and was a Groom-in-Waiting to HRH Queen Victoria and who died in 1868 unmarried.

The Baronetcy passed to Sir Henry John's brother, Sir Charles Hay Seton in 1868, and then to Sir Bruce Maxwell in 1869.

He married Helen Hamilton, daughter of General Richard Hamilton, on the 30th January, 1886.  Sir Bruce was Deputy-Lieutenant for Tower Hamlets, and Private Secretary to the Lord President of the Council (1867-1874).  He was a great traveler as well as a renowned Administrator and retired as an Official of the War Office.  He and his wife Helen lived at Durham House, Chelsea, London.  They together were noted for entertaining with great hospitality at their London home.

He maintained throughout his life and avid collection of artwork, antiquities, objets-de-vertu, heirlooms and sketches, as well as various relics, such as: Queen Mary's lace collar, a silver snuffbox of Charles I, a gold ring of Charles I and a lock of the same king's hair (precious Stuart relics), an Andrea Ferrara claymore, Alexander Pope's reading chair, and a large Burmese sword belonging to a renowned dacoit named Bohshwey in India who had long terrorized a whole district there, which was obtained through hand-to-hand combat by General Hamilton (Sir Bruce's brother-in-law) while stationed in India.

Helen Hamilton herself was noted for her own accomplishments of painting and various administrative qualities, as well as being a remarkably accomplished writer and noted well by journals of the time on both sides of the Atlantic.  She was the "diamond" of Sir Bruce's life, an amazing beauty to whom he devoted his life to faithfully.  Archbishop Robert Seton, of the Parbroath family, mentions her with great admiration.