Gilbert G.P. Guilford

Gilbert is a slender, dark-haired, and bespectacled man. He is confidante and personal knight to the Second Princess Cornelia Li Britannia, and leads the Glaston Knights. His skill as a pilot matches that of Kyoshiro Tohdoh. His devotion to Cornelia is unwavering, even after her disappearance at the end of the first season.

First season
Shortly after arriving with Princess Cornelia, Guilford informs Jeremiah Gottwald of his demotion. During the battle of Narita with the Japanese Liberation Front, he squares off against Kyōshirō Tōdōh's Burai Kai in his Gloucester. The aftermath of battle at Narita revealed that all the Burai Kai Knightmares had been destroyed, indicating that Tōdōh had been forced to abandon his fight or was otherwise defeated. Gilbert continues to serve Cornelia until she is injured in the Black Rebellion. During the rebellion, he and the Glaston Knights ultimately routed the Black Knights, capturing Tōdōh and many other leading members.

Second season
In the second season, Guilford is still waiting for Cornelia to return, as she disappeared after the Black Rebellion. After Governor-General Carares is killed, Guilford serves as temporary Governor-General to Area 11. When Zero returns, taking refuge in the Chinese Federation Consul, Guilford tries to goad him into a duel by staging a public execution of the captured Black Knights. Zero uses the compartmentalized floor plating to dump the entire contingent of Britannian Knightmares, as well as the prisoners, onto Chinese Federation soil, allowing the Black Knights to easily dispatch the confused Britannians. Two of the Glaston Knights are killed in the battle.

During the attack on Nunnally's transport as she is being taken to Area 11, Guilford unexpectedly arrives piloting the recent mass-production model Vincent accompanied by the remaining Glaston Knights. Though the units prove superior at first, largely due to their flight capacity whereas the Black Knights' Knightmares were confined to the ship, Kallen Stadtfeld turned the tables with her upgraded Guren Aerial-Type, using its long range radiation blast to destroy two more of the Glaston Knights' Gloucesters and Guilford's Vincent, injuring him before he manages to eject. He is seen piloting another Vincent during the opening ceremony for the Special Administrative Zone of Japan, where he is angered by Suzaku Kururugi's refusal to order an attack on the crowd after they all dress as Zero to spurn Britannia. During the battle for Japan, Lelouch uses his Geass to make Guilford believe that he is actually Cornelia, turning Guilford to his side. Guilford sacrifices himself to push Lelouch (whom he still believes to be Cornelia) outside of the blast radius of the F.L.E.I.J.A. bomb, telling him to live on.