The St. Dunstan was built by Lobnitz and Co in 1894. At 730 grt, equipped with 2 triple expansion engines and 61m, she was not a pretty site and just one the many workhorse deployed to keepg the harbour and shipping lines clear. Not much is known about her services and where she operated, except that her last civilian captain was
She was captained by Thomas Morgan. As World War I was taking its toll on the British shipping lanes, the Admirality requistioned her (like anything else they could get their hands on) to keep the vital shipping lanes open. She was converted to work as a dredger / mineclearer and Sub-Lieutenant Charles Gray was in charge.
On 23. September 1917, a large explosion rocked her. Initially, everyone believed she had been torpedoed, but minesweeper clearance later proved it to be the work of the UC21 under command of Werner von Zerboni di Sposetti. The UC21 was famous later for being under the initial command of Reinhold Saltzwedel, whose name was used to name the 2nd Flotilla. Zerboni di Sposetti would have been likely given orders to deploy all his mines in the key shipping channels - five of the 18 mines a UC II U-boat (Minelayer U-Boat) could carry were recovered and identified later after the sinking of the St. Dunstan.
Charles Gray ordered an immediate evacuation by ordering everyone to jump overboard into the water. He had enough time to through a few lifebuoys overbaord before jumping himself into the water. Within 4 minutes she turtled and sank to the bottom. 19 of 21 crew were saved by passing trawler escorts, first mate John Obery and deckhand Edward Warren died.