I would be shocked if SZD would attract, or rely on, island destinations (Highlands, Channel or Scilly) so I don't think it affects the discussion about SZD, even though the Scillies had slipped my mind. (easily done)
There are a very limited number of Twin Otters and Islanders. Don't start raising the hopes of people in Sheffield, otherwise the Scillies will be overrun.
And you didn't pick up on Dundee!