The King Cadwallon was build in 1900 by Rodger A. & Co in Glasgow and was equipped with a 278hp triple expansion engine. She had a single shaft and screw and was designed as bulk cargo carrier. Initially owned by McLaren & Mclaren of Glasgow under the name of SS Edderton. . She was sold to Philips, Philipps and Co. Ltd - King Line, London in 1904 who renamed her King Cadwallon.
On her last voyage, she was leaving Barry Docks loaded with over 5,000 tonnes of coal. Their destination was Naples and the planned route was to sail south-west along coast, sail south and follow a run down the Alantic Coast, via Gibralter to Naples. However, Captain George Mowat and his 26 crew were engulfed by heavy fog as soon as they left Barry on 21st July 1906. The fog lifted briefly, allowing the Captain to determine their position as being just off Lundy Island in the Bristol Channel. However, the fog engulfed them shortly later again and by the time they reached the Scilly Isles, they were lost. Captain Mowat knew he was near the Islands, but not exactly where. Reducing speed and checking their depth every few minutes, which reported 50m+ of depth, Captain Mowat was certain they were in deep water. Three minutes after the last check, they hit the rocks.
At 5 a.m. on 22nd July 1906, the ship struck the highest point of the Hard Lewis Rocks. Her engines were shut down immediately and she started to take on water fast, listing heavily to her starboard side. The Captain ordered the ship to abandoned and they took to the boats with their personal belongings. At that moment, the fog lifted. They were rescued shortly later and watched as the King Cadwallon slipped backwards down the rocks into the sea. She sank more or less upright and sits now in 50m of water.