Guest Stars Rupert Young as Sir Leon Eoin Macken as Sir Gwaine Tom Hopper as Sir Percival Tomiwa Edun as Sir Elyan Alexander Vlahos as Mordred Sophie Rundle as Sefa Liam Cunningham as Ruadan Lindsay Duncan as Queen Annis Stephen McCole as Ragnor Julian Glover as Lochru Josette Simon as The Euchdag