Here we see the ST Challenge at Bristol City Docks in 2004.
Challenge is the last steam tug to have worked on the Thames and took part in Operation Dynamo in May 1940 to evacuate British and French troops from Dunkirk. She is listed on the National Register of Historic Vessels "Core Collection" A small and dedicated group of volunteers keep her in full working order today. Challenge is now owned by the Dunkirk Little Ships Restoration Trust.
For more information on this wonderful example of a British Steam tug please have a look at http://www.stchallenge.org/