Two entries with the name Londres.
Londres
In La Tavola Ritonda, the capital of King Anguish of Ireland, father of Isolde.
In other sources, it is a variation of London.
Source
La Tavola Ritonda | 1325–1350
Londres
A king after whom London was named. Londres was the father of Constantine, Arthur’s grandfather.
Source
Unknown (the pre-Arthurian period) | Baudin Butor, c. 1290