Gilbert Forrest Bagnani was born April 26, 1900, in Rome, to General Ugo Bagnani, of Rome and later London as military attache at the Italian Embassy, and Florence Dewar, daughter of Dr. James Dewar of Cobourg, Ontario. Gilbert spoke both English and Italian and later learned to speak Greek, Latin, Arabic, French and German. He was educated at the Nobile Collegio del Nazzareno in Rome and at a preparatory school called Gibbs' in London. His schooling was interrupted by World War I. He served as a Second Lieutenant of artillery towards the end of the War. After the War he returned to the University of Rome where he received his doctorate. Instead of entering law as he had planned, he turned to the Italian School of Archaeology in Athens to study antiquities which were becoming a strong interest of his.
In 1929 Gilbert married Mary Augusta Stewart Houston of Toronto, daughter of Stewart Houston (editor of "The Financial Post") and Augusta Robinson (daughter of John Beverley Robinson, Lieutenant-Governor of Ontario, and granddaughter of Sir John Beverley Robinson, Chief Justice and Attorney-General of Upper Canada). Stewart's father died while she was young and her mother took her to Europe for a more cosmopolitan education than she could receive in Canada. Gilbert and Stewart had an apartment in Rome and for seven seasons worked, in the Sahara Desert, with the Royal Archaeological Mission to Egypt.
In 1937 they fled fascist Italy and purchased a 200 acre farm and house built around 1845 near Port Hope, Ontario and named it "Vogrie". They added a large, forty foot long, two storeys high addition in which they housed their library, oil paintings, drawings, tapestries and ceramics. In 1945 Gilbert was invited to teach ancient history at the University of Toronto and in 1958 he became a Professor. He retired from the University of Toronto in 1965. During the time that the Bagnanis were in Toronto, Gilbert was a founding member and president of the Oriental Club of Toronto, a supporter of the Art Gallery of Ontario and an active member of the Archaeological Institute of America, of which he was vice-president from 1951 to 1954. Stewart was head of Extension at the Art Gallery of Ontario from 1951 to 1963. In 1965 the Bagnanis returned to "Vogrie". In the same year, Gilbert was asked to accept a term-appointment at Trent University. He was honoured with a LL.D. by Trent in 1971 and he continued to teach as a Professor of Ancient History until 1975. During the period between 1965 and 1975 Stewart remained active, lecturing on art in various venues and developing the Mackenzie Gallery at Trent University. Gilbert and Stewart did not have children. On February 10, 1985 Gilbert Forrest Bagnani died. Stewart moved to their Toronto home. In May of 1996 Mary Stewart Houston Bagnani died. The "Vogrie" property was inherited by Trent University after the death of Gilbert in 1985. Antiquities, art works, furniture, books and documents were bequeathed to a number of institutions, including Trent University, after the deaths of Gilbert and Stewart Bagnani.