Many elements and incidents that are now an integral part of the Arthurian story appear in Geoffrey's Historia, including Arthur's father Uther Pendragon, the wizard Merlin, Arthur's wife Guinevere, the sword Excalibur, Arthur's conception at Tintagel, his final battle against Mordred at Camlann and final rest in Avalon.

Geoffrey's account of Merlin Ambrosius ' early life in the Historia Regum Britanniae is based on the story of Ambrosius in the Historia Brittonum.

While Nennius ' Ambrosius eventually reveals himself to be the son of a Roman consul, Geoffrey's Merlin is begotten on a king's daughter by an incubus.

In Robert's account, as in Geoffrey's Historia, Merlin is begotten by a demon on a virgin as an intended Antichrist.

* Prophetiae Merlini: Geoffrey presented a series of apocalyptic narratives as the work of the earlier Merlin who, until Geoffrey's book came out, was known as " Myrddin ".

It is not until the 13th-century French prose romances, including the Lancelot-Grail and the Post-Vulgate Cycle, that Camelot began to supersede Caerleon, and even then, many descriptive details applied to Camelot derive from Geoffrey's earlier grand depiction of the Welsh town.

Geoffrey's description of Caerleon is probably based on his personal familiarity with the town and its impressive Roman ruins ; it is less clear that Caerleon was associated with Arthur before Geoffrey.

Rhongomyniad (" spear " + " striker, slayer ") is also first mentioned in Culhwch, although only in passing ; it appears as simply Ron (" spear ") in Geoffrey's Historia.

While usually harmless, Mike is not above using underhanded tactics to get his way — in A Hole in the Heart ( series 3 ), he steals a story from Marty because viewers are responding positively to it, while in Addicted to Fame, he demands that Geoffrey's television show be cancelled because he is jealous of the attention his friend is getting.

How much of Geoffrey's Historia ( completed in 1138 ) was adapted from such earlier sources, rather than invented by Geoffrey himself, is unknown.

Although the themes, events and characters of the Arthurian legend varied widely from text to text, and there is no one canonical version, Geoffrey's version of events often served as the starting point for later stories.

How much of this narrative was Geoffrey's own invention is open to debate.

However, while names, key events and titles may have been borrowed, Brynley Roberts has argued that " the Arthurian section is Geoffrey's literary creation and it owes nothing to prior narrative.

There have been relatively few modern attempts to challenge this notion that the Historia Regum Britanniae is primarily Geoffrey's own work, with scholarly opinion often echoing William of Newburgh's late-12th-century comment that Geoffrey " made up " his narrative, perhaps through an " inordinate love of lying ".

Geoffrey Ashe is one dissenter from this view, believing that Geoffrey's narrative is partially derived from a lost source telling of the deeds of a 5th-century British king named Riotamus, this figure being the original Arthur, although historians and Celticists have been reluctant to follow Ashe in his conclusions.

The popularity of Geoffrey's Historia and its other derivative works ( such as Wace's Roman de Brut ) is generally agreed to be an important factor in explaining the appearance of significant numbers of new Arthurian works in continental Europe during the 12th and 13th centuries, particularly in France.

There is clear evidence for a knowledge of Arthur and Arthurian tales on the Continent before Geoffrey's work became widely known ( see for example, the Modena Archivolt ), as well as for the use of " Celtic " names and stories not found in Geoffrey's Historia in the Arthurian romances.

Whereas Arthur is very much at the centre of the pre-Galfridian material and Geoffrey's Historia itself, in the romances he is rapidly sidelined.

Although the Mabinogion tale The Dream of Macsen Wledig is written in later manuscripts than Geoffrey's version, the two accounts are so different that scholars agree the Dream cannot be based purely on Geoffrey's version.

One triad, based on Geoffrey's Historia, provides an account of his betrayal of Arthur ; in another, he is described as the author of one of the " Three Unrestrained Ravagings of the Isle of Britain " – he came to Arthur's court at Kelliwic in Cornwall, devoured all of the food and drink, and even dragged Gwenhwyfar ( Guinevere ) from her throne and beat her.

One might suppose Rica to be another name for Gorlois ( though Welsh translations of Geoffrey name him Gwrlais ), but we also have in Geoffrey's account a Gormant the Irish who is king of Ireland ( based on the villain of the French chançon de geste called Gormant et Isenbart ) and this Gormant might be hiding here also as Gormant ap Rica, this being a possible corruption of Gormant Ireland.

Although the Mabinogion tale Breudwyt Macsen Wledic ( The Dream of Macsen Wledig ) is written in later manuscripts than Geoffrey's version, the two accounts are so different that scholars agree the Dream cannot be based purely on Geoffrey's version.

Historically, the predecessor to Constantine was Gratian on whom Geoffrey's tale was probably based.

This account is so different from Geoffrey of Monmouth's account of Maximian ( as Geoffrey calls him ) in Historia regum Britanniae that scholars agree the Dream cannot be based purely on Geoffrey's version.

Geoffrey's account of the episode is based on Constantine's murder of two " royal youths " as mentioned by the 6th-century writer Gildas.

An earlier Smiths song, " This Night Has Opened My Eyes ", is based on the play and includes Geoffrey's line to Jo near the end: " The dream has gone but the baby is real.

Geoffrey's description in turn drew on an already established tradition in Welsh oral tradition of the grandeur of Arthur's court.

As a result of this popularity, Geoffrey's Historia Regum Britanniae was enormously influential on the later medieval development of the Arthurian legend.

Seen positively, Stephen stabilised the northern border with Scotland, contained Geoffrey's attacks on Normandy, was at peace with Louis VI, enjoyed good relations with the church and had the broad support of his barons.

King Henry I of England, having heard good reports on Geoffrey's talents and prowess, sent his royal legates to Anjou to negotiate a marriage between Geoffrey and his own daughter, Matilda.

The following year, Geoffrey gave Ambrieres, Gorron, and Chatilon-sur-Colmont to Juhel de Mayenne, on condition that he help obtain the inheritance of Geoffrey's wife.

Seen positively, Stephen stabilised the northern border with Scotland, contained Geoffrey's attacks on Normandy, was at peace with Louis VI, enjoyed good relations with the church and had the broad support of his barons.

Several later works expand on Geoffrey's mention of Gawain's boyhood spent in Rome, the most important of which is the anonymous Medieval Latin romance The Rise of Gawain, Nephew of Arthur, which describes his birth, boyhood and early adventures leading up to his knighting by his uncle.

In the midst of the Arthurian section of the text, Wace was the first to mention the legend of King Arthur's Round Table and the first to ascribe the name Excalibur to Arthur's sword, although on the whole he adds only minor details to Geoffrey's text.

Geoffrey's Historia Regum Britanniae expands on the legend of Coel, including material about his rule as king of the Britons and his dealings with the Romans.

During Geoffrey's term of office as Chancellor Walter de Coutances served as his " seal-keeper "; the need for someone to perform this function adds further evidence to the likelihood that Geoffrey's time as Chancellor was spent on unrelated duties for his father.

Geoffrey's ordination as a priest took place at Southwell on 23 September 1189, in a ceremony performed by John the Bishop of Whithorn.

Although Hugh du Puiset, who was Justiciar, was hampering Geoffrey's attempts to collect revenue for the earlier fine, Richard insisted on immediate full payment.

Another complication was that the English bishops had appealed to the papacy because Geoffrey had not been consecrated by the Archbishop of Canterbury, and Longchamp could therefore claim to have been acting on behalf of the other bishops in ordering Geoffrey's arrest.

* Vita Merlini: This is in part Geoffrey's retelling of the earlier Myrddin legend from Welsh tradition, but includes numerous other source materials as well, and includes elements of the tradition of saints ' lives as well as the sort of encyclopaedic knowledge of the natural world and the heavens then in vogue at Oxford.

The King also held the substantial estate of Geoffrey's maternal grandfather Eudo le Dapifer to which Geoffrey laid claim.

Geoffrey's half-brother Richard I, also known as " Richard Lionheart ", nominated him Archbishop of York after succeeding to the throne of England, probably to force him to become a priest and thus eliminate a potential rival for the throne.

His military abilities, displayed in the rebellion of 1173 – 1174, as well his custody of castles near Tours, would have also fed into Richard's disquiet over Geoffrey's possible intentions.

He is also mentioned in the tale Lludd and Llefelys, which features his two brothers Lludd Llaw Eraint ( Geoffrey's Lud ) and Llefelys.

He should also not be confused with Eldol, Consul of Gloucester who lives generations later in Geoffrey's work.