ROCK, United Kingdom, ??gt, completed London and Rochester, Frindsbury, 1961
1990 withdrawn from service - sold to private owners

A bit of a nebulous link to Dunston at Thorne simply because it is stated they designed this class of small Medway coasters.
See: http://www.hcmoorings.org/vessels-at-hcm/rock/

On the Thames - 15 July 2013: Ron

Interesting Ron, as they don't seem to have built any of the class at Thorne.

Better link was that she was owned by Roy Mills of Goole between June 1980 and February 1986.