Guy Francis is the author of A catalogue of the armour and arms in the armoury of the Knights of st. John of Jerusalem, now in the Palace, Valetta (1903), Catalogue of the European Armour and Arms in the Wallace Collection at Hertford House ... (1901), Catalogue of the European Armour and Arms in the Wallace Collection at Hertford Hous (1901), Catalogue of the European Armour and Arms in the Wallace Collection at Hertford House, Mr. Edward Barry's Collection of Arms and Armour at Ockwells Manor, Bray.