There is normally one Twin Otter based at St. Just (at least it was so as I made my flights in April), but as said above normally used to the more distant airports.
Here are two of them at St. Marys
The British International S-61Ns are getting old, and I suspect they aren't the most cost effective among the helicopters these days. It's sad to see them go, but this day had to come. Maybe why I did the trip in April just to have done it? I missed out Plymouth with a few days because of the radar coverage, but this time I made it.
Cabin view on the return flight from Tresco