Bruton is a brooding, mysterious market town in south-west England, hardly the place you'd expect someone born and raised in sun-blessed California to come to love. But Californian author John Steinbeck, who lived there from March to October 1959, pronounced on his deathbed that his six months there were the happiest of his life.

"Time loses all its meaning. The peace I have dreamed about is here," he wrote.

The seeds for Steinbeck's Somerset sojourn were sown on his ninth birthday by his Aunt Molly, who gave him a children's version of Sir Thomas Malory's Le Morte d'Arthur as a present.

Malory's late-15th century reworking of the Arthurian legend featuring King Arthur, Guinevere, Lancelot, Merlin and the knights of the Round Table has intrigued and inspired many modern writers (including T.H. White with his popular fantasy novel The Once and Future King). Steinbeck was to be no exception.

Steinbeck and his gregarious wife, Elaine, rented a small place outside Bruton, an ancient two-chimneyed home called Discove Cottage, some distance from the town centre.

"People knew he was here but seem to have kept a polite distance," says Andrew Pickering, program manager for Plymouth University's history, heritage and archaeology degree delivered at nearby Strode College. However, "pupils from the school would ride out to see the great author to discuss poetry and novels with him – many were studying Of Mice and Men for their English exams," he says.

"Steinbeck loved Bruton because of the slower pace of life and because he felt living here put him in touch with his Anglo-Saxon ancestors – as well as the stunning countryside and its rich history and heritage, he adored the local accents."

Turns out, there was an exchange of accents the other way, too.

In Bruton's charming little museum there's a note by Steinbeck that says: "As I knew she would, Elaine is seeding Somerset with a Texas accent. She's got Mr Windmill of Bruton saying 'you-all'. At this moment she is out in the gallant little Hillman [car], calling on the vicar and getting in some booze. She'll probably bring both back with her."

The museum contains not only John Steinbeck's desk but an entire drawer of Steinbeck memorabilia that a volunteer helper will show you if ask nicely. The desk is the highlight, a wooden construction of the author's own design, built to be placed on top of a table so he could write while standing.

"My neck and shoulders don't get so damn tired," he explained.

When Steinbeck arrived, the ancient settlement of Bruton was a small town, possibly the smallest in England, and he loved the area's association with the Arthurian legends. The Iron Age hill fort of South Cadbury moved him to tears, not just because it was reputed to be the site of Camelot but also because of its beautiful views. And he took part in archaeological excavations at Glastonbury Abbey and the Roman temple site of Lamyatt Beacon.

It's hard to know what he'd make of it now. The Hauser & Wirth contemporary art complex opened in 2014 and attracts more than 100,000 visitors a year, celebrities abound, and Vogue ran a seven-page spread on the town and its residents. "It made us look like something out of Hello!" said one dismayed local in The Times. Thankfully, despite all the hoo-ha, Bruton retains an intriguingly intimate feel. 

Although Steinbeck was happy in Bruton, his time there professionally was not a great success.

"The Morte d'Arthur defeated him," say Pickering. "I guess because it was his own Holy Grail and hence forever out of reach. He seems to have been pleased with his work on the Winchester Manuscript [the earliest surviving version of Malory's work]. But it was rubbished by his editor, who wanted something more populist and along the lines of T.H. White's Once and Future King."

Steinbeck's professional despondency may have been deepened by his identification with Lancelot. "He found Arthur's character unrealistic whereas Lancelot was very human – a man, like him I guess, devoted to good deeds but full of human frailty," says Pickering.

Dejected by the rejection of his life's most important project – and after writing his last letter from Bruton in the Blue Ball Inn, now converted into tourist accommodation – he and Elaine left their beloved town in October 1959.

Of their departure, Elaine said: "It was hard to leave England at that time, John had discovered something about himself at Discove Cottage."

Poignantly, she also said: "Bruton is the only spot in the world I have refused to see again since John died."

Steinbeck's incomplete novel, The Acts of King Arthur and His Noble Knights, was published posthumously in 1976.

Roger Balch travelled to and stayed in Bruton independently.