one of the current twotters is G-BIHO which i used to handle when it was in service with Brymon! late 1980's
Brymon when they got their new 50 seat Dash-7's they thought about ops to St Marys with those but that never came to fruition - i think one test flight was done
I always thought a Dash 7 would do them well now but then you start to have to bow to security issues (diff rules over 19 pax) both at ISC and Lands End airports which are not in that category and the costs soar