In the pseudo-chronicles, the Historia of Geoffrey and the translations by Wace and Layamon, Lancelot does not appear at all; the queen's lover, whose guilty passion is fully returned, is Mordred.
In the next century the influence of Geoffrey is unmistakably attested by the Brut of Layamon, and the rhyming English chronicle of Robert of Gloucester.
Geoffrey of Monmouth makes no mention of it, and the earliest record is that of Wace, much expanded by his translator, Layamon, who gives a picturesque detailed description of the fight for precedence which took place at Arthur's board on a certain Yuletide day, and the slaughter which ensued.
When the founding of the Round Table is ascribed to Merlin it is generally in close connexion with the Grail legend, forming the last of a series of three, founded in honour of the Trinity - the first being the table of the Last Supper, the second that of the Grail, established by Joseph of Arimathea, The number of knights whom the table will seat varies; it might seat twelve or fifty or a hundred and fifty; nowhere, save in Layamon, do we find a practically unlimited power of accommodation.
It is difficult to explain this phrasing in any other hypothesis than that Layamon pictured to himself Arthur's hall as open on one side, and that, on a great feast-day, owing to the number of guests, the table extended beyond the covering afforded by the roof.