Pellinore has not forgotten his kingdom in Malory, as he has in the musical 'Camelot'. He is King Pellinore of the Isles. Since two of his sons are Percivale and Lamerake of Wales (or, de Galis), his Isles could be in or near Wales. Anglesey and Holyhead Islands off the coast of northern Wales would answer this description.
Study of the works of Chrétien de Troyes gives an alternative interpretation. In notes to line 419 of 'Perceval', both D.D.R. Owen and Ruth Cline identify the Isles of the Sea (Owen's translation), also known as the islands of the sea (Cline's), as the Hebrides, Cline citing the authority of hilka. In the passage including line 419, Percivale's mother tells him that his father's name (which Chrétien does not reveal) was known throughout the Isles of the Sea; again, in and around line 4093, Gawaine remarks that he has never known or heard of any knight from all the islands of the sea whose feats could rank with Percivale's.
Apparently the same islands are meant in both passages. The context of these references, coupled with the surprising number of characters Chrétien includes, especially in Perceval, surnamed "of the Isles", causes me to wonder whether the islands in question could conceivably be the British Isles themselves.
Estrangor, Estrangot, Lo Leu Estrange
The Castle was strong, with but one narrow entrance. The name suggests an island or perhaps a valley. The place is probably small, and may be near the "Forest of the Boiling Well". I believe it is probably close to Carteloise Forest in southern Scotland.
Isle of Anglesey
An island in the Irish sea. [More]
Isle of Apples
The name used by Geoffrey in his Vita Merlini to refer to Avalon, the paradisiacal land of the dead. The use of this name possibly derives from the Irish Emhain Abhlach, an island that is associated with the Irish god of the sea Manannán Mac Lir and whose name means 'Emhain of the Apple Trees'. Irish tradition makes this island the Isle of Arran.
Isle of Honey
An early name for Britain, according to the White Book of Rhydderch.
Isle of Life
A place, possibly to be identified with the Isle of Wight, where the ancient British kings Gaddifer and Perceforest were said to have enjoyed a prolonged existence. This life-prolonging island seems to have connections with the Isle of Apples, which Geoffrey of Monmouth makes Avalon, and, by association with Irish mythology, might possibly be identified with the Isle of Man.
Isle of Longtains
The kingdom of Galeholt. [More]
Isle of Maidens
See under "Isle of Maidens, King of the" below, and also under the Captive Damsels of Pesme Avanture.
I can find no further hints in Chrétien's romance Yvain as to the whereabouts and culture of this island kingdom itself.
Isle of Maidens, King of the
This young monarch was only eighteen when he went out seeking adventures and came to Pesme Avanture.
His experience there does not exactly cover him with glory - he looks like a feckless coward who cares more for his own skin than for his people's welfare - but at least the charge of malice is never laid against him.
Isle of Man
Falga, Mana, Manu, Manaw
A large island in the Irish Sea with a long Celtic history. Irish legend says that it was the island to which some of the Fomhoiré were exiled after their defeat by the people of Partholán, other exiles going to the Hebrides. Later tradition made it the home of Manannán mac Lir. Cormac mac Cuilennáin (fl. 900) attempted to establish Manannán mac Lir as a historical person by declaring him a magnificent navigator and merchant who hailed from the island, and by saying that it was these skills that led both the Irish and the British to regard him as a god.
The island was, during the traditional Arthurian period, ruled by a number of Celtic kings about whom very little is known. The enchanted knight Gromer became king with the help of Gawain. The island also figures in a tale concerning Merlin, who allegedly defeated a number of giants and interred them in caves beneath Castle Rushen on the island.
Recent works have attampted to connect the Isle of Man with Avalon, perhaps because of the naming of Avalon as the Isle of Apples by Geoffrey of Monmouth and the Irish connection of the island with Emhain Abhlach ('Emhain of the Apple Trees'), the home of the Irish sea god Manannán mac Lir.
Falga | The Legend of King Arthur
Môn | The Legend of King Arthur
'The Lost Island'
A retreat of Duke Galeholt's, this castle was thickly surrounded by woods and located on an island. Probably it was in or near Galeholt's favorite country, Surluse (Sorelois).
Do not confuse this Isle Perdue with those described with the entry for the castle of Meliot.
Lost Island | The Legend of King Arthur