I too would be interested in the history of the firm. All I do know is just a couple of snippets, picked up from (I think) Gareth Morris many years ago; I gather that the proprietor was known as “Barry the Boat”, and that they eventually closed down following a disastrous fire at their workshop round about year 2000, a fire which also destroyed vintage GP14 no. 10.
I suspect that Graham Knox will know something about their history, and possibly also Gareth.
I have likewise been impressed with their build quality, and I briefly owned one of their Series 1 boats, Strait Laced, no. 11930. I do know that they built in both wood and GRP.
For what it is worth I have tracked down a facebook page celebrating them, https://www.facebook.com/Don-Marine-105209796225888/, but that doesn’t give us any hard information about their history.
Oliver