Looking through the round window

Valentine, Drascombe Coaster No281

Daisy II is Drascombe Coaster No.280.  These details are etched on her brass stemhead, and also feature in the serial number.  Built, as she was, in July 1997, by a soon-to-be-insolvent Honnor Marine of Totnes, I've often wondered whether she was the last boat this particular firm ever produced.  I'm also intrigued by the cabin windows which are distinctively round, rather than the long oval shape found on most coasters.  Whilst not unique, I certainly feel these add a particular charm to the design, and I wouldn't want a model with the usual window.  How many more round-windowed examples are there?

I found out, this week, that Daisy II has a twin - Valentine - which currently is kept in Scotland and is  Coaster No281.  As well as being the ensuing hull number, she also features the same round windows and leads me to believe that HM did indeed produce at least one more coaster prior to calling in the receivers.  But, a few questions spring to mind:
 Firstly, how many more of these round-windowed coasters were built?  On the recent east coast cruise, we saw  coaster Virginia, which features three round windows on either side, but this is a rather earlier model.  Moreover, why did the builders suddenly start a run of round-windowed coasters - and were there any others in this particular run?