The Stronsay Beast carcass and the Orkney sworn statements

Stronsay, spelled Stronsa in 1808, is an island in Orkney. At its southwestern extremity lies Rothiesholm Head, a headland covered in heather and edged by steep cliffs. It was part of the estate of Gilbert Laing Meason. About 50 years earlier, Erik Pontoppidan had described sea serpents.

September 1808. A storm had passed. John Peace, a farmer and fisherman, was fishing just off Rothiesholm Head. He noticed seabirds gathering around what appeared to be an animal carcass lying on the rocks. Up close, it was a very peculiar-looking creature, draped over a submerged rock, and Peace broke off some of its bristles with his boathook.

From the shore, another farmer, George Sherar, was watching Peace. He could confirm all of it. Then he waited for the sea to bring the carcass in. Most accounts give the date as 25 September 1808. Karl Shuker puts Peace's sighting on 26 September and the stranding about 10 days later.

Three men measured it: Sherar, Peace and Thomas Fotheringhame, a house carpenter from Kirkwall. They reported the same result: 55 feet, not counting the missing part of the tail, with a circumference of about 10 feet and a width of 4 feet at the thickest point. They described a very serpentine, almost eel-like body, with a 15 ft neck ending in a small, seal-like head and eyes about the size of a seal's. It had three pairs of appendages, called paws or wings, with five or six toes on each foot, and a mane of eighteen-inch filaments running from the shoulders almost to the tail that glowed when wet in the dark. The grey, unscaled skin felt smooth from head to tail and rough in the other direction.

November 1808. The witnesses were taken to Kirkwall to swear before the magistrates. Declarations by John Peace, George Sherar, William Folsetter, William Strang Petrie and Thomas Fotheringhame, dated the 10th, 19th and 24th of November 1808, survive in the archives of the Royal Society. A Mr Petrie made an ink scale drawing, now in the Orkney Museum. Sherar later agreed that a sketch printed in 1811 was "an exact resemblance".

19 November 1808. In Edinburgh, Patrick Neill read an account from Mr Urquhart of Elsness to the Wernerian Natural History Society, accompanied by four vertebrae. The Society decided it was a new species, probably a sea serpent, and on 14 January 1809 Neill named it Halsydrus pontoppidani, Pontoppidan's sea-snake. The anatomist John Barclay examined the vertebrae, skull and a leg. As Bill Jenkins puts it, his 1811 paper treated the remains as "the first solid scientific evidence for the existence of the 'great sea snake'".

In London, Sir Everard Home of the Royal Society discounted the testimony. It was a decomposed basking shark, he said, about 30 ft long. John Goodsir agreed in 1849.

Most modern writers agree with Home. A rotting basking shark becomes a pseudo-plesiosaur. The jaw and gills fall away, leaving a small "head" on a long spine. Fin rays and fraying muscle look like a mane. Fins look like legs, and a male's claspers like a third pair.

One problem remains. The largest confirmed basking shark measured 40 ft 3 in. The Stronsay men measured 55. Shuker has suggested an undescribed larger relative of the basking shark.

Three vertebrae are held at the National Museum of Scotland. More bristles lie in the John Murray archive at the National Library of Scotland. The skull was destroyed in the London Blitz. Dr Yvonne Simpson, later Beale, has studied the remains since 2001. She proposed DNA testing in 2008. No result has been reported.