Portmeirion where Patrick McGoohan's TV series, The Prisoner, was filmed in 1967. See also here and here. Because I visited the setting of the Village while still thinking about Poul and Karen Anderson's The King Of Ys, I drew several comparisons that would not otherwise have occurred to me.
(i) A British Roman centurion on a mission to Armorica becomes King (rex) of Ys. A British secret agent resigns, is abducted and becomes No 6 (sex) in the Village.
(ii) The Village is an island prison designed as a seaside holiday camp or retirement resort with a beach. Ys is a small walled coastal city of free citizens but with two similarities to a prison:
below the rising sea level, it is hostage to the sea god;
the King is expected to remain in Ys and Gratillonius might have to fight his way out;
for him, "Emergence..." from the sea god's temple "...was like release from captivity." (Gallicenae, p. 254)
(iii) Buildings are decorated with mermaids and sea shells in Ys and in Portmeirion - therefore probably also in the Village.
(iv) King Gratillonius contends with Lir Captain, the Speaker for Taranis, the Nine Witch-Queens, the Council of Suffetes and beyond them the mysterious Triad. No 6 contends with the new No 2, bureaucrats, surveillance cameras, security guards, loyal citizens' committees and beyond them the mysterious No 1.
(v) Despite (ii), Gratillonius is soon at home in Ys whereas No 6 briefly returns home yet remains alienated. Someone else is living in his apartment at 1, Buckingham Place, and driving his car and his unknown abductors are still at large and active.
(vi) It may be No 6's own government that incarcerated him. He might consider defection. The Roman Empire forfeits Gratillonius' allegiance. He concentrates on defending Armorica - and by irregular means.
(vii) The Triad destroys Ys. No 6, realizing his identity with No 1, is no longer bound by the Village which has metamorphed into an allegory for society.
(viii)-(x) to follow here.