Novels

• Knight with Armour (1950). The First Crusade, from the viewpoint of a rather ordinary knight
• Conscience of the King (1951). A speculative life of Cerdic, the founder of Wessex
• The Little Emperors (1951). A succession of coups in late-Roman Britain.
• Lady for Ransom (1953). Norman mercenaries from the West serving the Byzantine Empire in the 11th century
• Leopards and Lilies (1954) A noblewoman seeking her own advantage in the dangerous politics of England under King John
• God and My Right (1955). The life of St Thomas Becket
• Winter Quarters (1956). Two Gauls in the time of Julius Caesar. One of them believes himself to be under a curse from the Mother Goddess, whose worship he finds throughout the Roman world.
• Three's Company (1958) the career of Lepidus, triumvir with Octavian and Marcus Antonius after the death of Julius Caesar
• Founding Fathers, U.S. title, Children of the Wolf (1959). Romulus and the founding of Rome
• The Cunning of the Dove (1960). The career of Edward the Confessor, told by one of his servants
• The King of Athelney, U.S. title, The Right Line of Cerdic (1961). The life of Alfred the Great
• Lord Geoffrey's Fancy (1962). Life in one of the short-lived Crusader kingdoms in Greece, told by an ordinary knight
• Elephants and Castles, U.S. title, Besieger of Cities (1963). The life of Demetrius I of Macedon, one of the Successors after the death of Alexander the Great.
• Family Favourites (1963). An ordinary Roman soldier witnesses the reign of Emperor Elagabalus
• Count Bohemond (1964). Another account of the First Crusade, this time from the viewpoint of Bohemond, one of its leaders

Non fiction

• Thomas Becket of Canterbury (1952)
• Julius Caesar: A Great Life in Brief (1955)
• My Life for My Sheep: Thomas a Becket (1955)
• He Died Old: Mithradates Eupator, King of Pontus (1958)
• Devil's Brood: The Angevin Family (1957)
• Look at Castles (1960). For young readers.
• The Castle Book (1961)
• Look At Churches (1961)
• Growing Up in Thirteenth Century England (1962)
• The Story of the Crusades 1097-1291 (1963)
• The Romans (1965). For young readers.
• Growing up with the Norman Conquest (1965)
• The Falcon And the Dove: A Life of Thomas Becket of Canterbury (1971)