Yes,
But not even Brymon considered scheduled DHC7's on ISC routes, to round up groups of Y50's to head, point to point, to/from the guest houses of the Scillies would be nigh on impossible and, if at all possible, only on Saturdays (weather permitting) taking in to consideration that ISC is closed on Sundays.
Brymon only ever looked at the possibility of DHC7's in/out of ISC after a Saturday of fog when ISC would temporarily open on the Sunday to get as many punters in in as short a time as possible.