CORONIA was built as BRIT by Fellows & Co., Great Yarmouth, in 1935 for Longfield Brothers
In 1950, she was modified with a lower funnel and bridge to be operated on the Thames by Thames Launches for excursion work during the Festival of Britain.
From 29 May 1940, HMT Watchful was deployed to assist in the Dunkirk evacuation for the whole nine days of operation Dynamo.
Then did another three trips back and saved another 900 men unsupported.
During the operation she managed to return unscathed.