The man behind the Ancient Mariner, the unsettling character who holds a wedding guest spellbound with his "glittering eye" in Coleridge's poem, has been unearthed by a writer from Shropshire.

Robert Fowke has traced the sailor and privateer whose story inspired the poet back to his birthplace in the Oxfordshire town of Woodstock, and has revealed the details of his extraordinary life in a book published this week.

Samuel Taylor Coleridge is thought to have come up with the idea of writing about a sailor who is becalmed at sea after shooting an albatross in 1797, while he was out walking with his friend William Wordsworth in the hills above his home in Nether Stowey, Somerset.

A statue of the mariner stands in the harbour of the nearby town of Watchet, marking the place where Coleridge is supposed to have stared out across the sea, imagining the plot of his poem.

"Scholars have always known what gave Coleridge the idea for the poem, because Wordsworth said they had talked together about a book by Captain George Shelvocke during their walk, but nobody has ever taken up the story," said Fowke this weekend.

Examining both Captain Shelvocke's A Voyage round the World by way of the Great South Sea (1726), and another seafaring volume by William Bettagh, Fowke has pieced together the life of the sailor, Simon Hatley, who is said to have shot down "a black albatross" while on board a ship called the Speedwell. "The more I discovered, the more exciting it was," said Fowke. "I knew Hatley was lost at sea and had then been picked up by a Spanish ship and taken to Lima, where I suspected he had become caught up in the Inquisition."

Finding an account that suggested Hatley was tortured in South America, Fowke travelled to Madrid to search through the Inquisition's official records. "Under the heading 'Spontaneous Conversion' I found at Number 11 a 'Simon Hatey' who was from 'Yudstock'. I thought that could be Woodstock, so I went to Oxfordshire and, sure enough, I found the birth of Simon Hatley in the local register for 1685."

Hatley sailed to the Pacific on two of the most dangerous voyages of the early 18th century. But perhaps the most amazing fact uncovered by Fowke is that, at one point, he was on a ship not only with Alexander Selkirk, the marooned sailor whose story inspired Daniel Defoe's Robinson Crusoe, but also with William Dampier, an adventurer and writer on whose work Jonathan Swift drew for Gulliver's Travels.

Hatley was on the crew of the Duke, which set out for South America on a voyage proposed by Dampier accompanied by a sister ship, the Duchess. At one point on this voyage of 1709, while Selkirk and Dampier were both together on board the Duchess, Hatley joined them. "Because these privateers were incredibly bureaucratic and suspicious and wrote down everything about their loot," explains Fowke, "they appointed Hatley as the 'plunder manager', to check that the two ships' crews were being honest with each other. So for one period they were all on board the same ship."

The Real Ancient Mariner, by Robert Fowke, is published by Travelbrief at £15.99.