Studioso di politica e scienze sociali e genealogista. Figlio di Carl Oskar Cristoffer e Sigrid Sofia Maria Sandell, studiò a Oxford e Stoccolma.
Pareto curò nel 1919 la prefazione al suo libro Politique financière d'aujour-d'hui principalement en considération de la situation financière et économique en Suisse.
Tra le sue opere: British and continental labour policy: the political labour movement and labour legislation in Great Britain, France, and the Scandinavian countries, 1900-1922 (1923); Issues of European statesmanship (1926); Origins and History of the Montgomerys: Comtes de Montgomery, Ponthieu, Alençon and La Marche, Earls of Arundel, Chichester, Shrewsbury, Montgomery, Pembroke, Lancaster, Mercia, Eglinton and Mountalexander, Princes de Bellême, Marquis de Montgomery de Lorges (1948); Ancient Migrations and Royal Houses (1968).
Cfr.Wikipedia. The free encycopedia, 10 set 2022, sub voce Bo Gabriel Montgomery, pubbl. elettronica, url https://en.wikipedia.org/wiki/Bo_Gabriel_Montgomery