Hi Steve,
Trawled through my various books, Dunkirk Little Ships etc and nothing shouts out, but Rampart looks favourite,
a thought - measure the hull in inches, lets assume it's inch to the foot,
then try Googling Rampart 46? or whatever the hull length is.
Another idea could be taking some good pics and sending them to my favourite boat yard "Harbour Marine Services"
at Southwold where they specialize in restoring similar full size old cruisers to a very high standard,
posted a couple of pics below from last years hols to give an idea.
HMS are on the web and Faceache book etc but it might be worth sending them some hard copies to pass round amongst
their staff, great bunch of guys let you crawl of the boats to take piccies etc.
Paul - Wallace & Gromit KLMBC