According to the authority given below, Winchester was the Camelot of Arthurian romance. Hanmer, referring to King Lear, ii. 2, says Camelot is Queen Camel, Somerset-shire, in the vicinity of which “are many large moors where are bred great quantities of geese, so that many other places are from hence supplied with quills and feathers.” Kent says to the Duke of Cornwall -
Goose, if I had you upon Sarum Plain, I'd drive ye cackling home to Camelot.
With all due respect to Hanmer, it seems far more probable that Kent refers to Camelford, in Cornwall, where the Duke of Cornwall resided, in his castle of Tintagel. He says, “If I had you on Salisbury Plain [where geese abound], I would drive you home to Tintagel, on the river Camel.” Though the Camelot of Shakespeare is Tintagel or Camelford, yet the Camelot of King Arthur may be Queen Camel; and indeed visitors are still pointed to certain large entrenchments at South Cadbury (Cadbury Castle) called by the inhabitants “King Arthur's Palace.”
“Sir Balin's sword was put into marble stone, standing as upright as a great millstone, and it swam down the stream to the city of Camelot - that is, in English, Winchester.” —History of Prince Arthur, 44.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894