Ah right.
Anyway, according to the website, I was right, sort of - the 'Sightseers round trip' is only bookable 30 mins prior to the flight
For half price (£31.00, you can go for a round trip from Kirkwall to Kirkwall via most of the other places, including the 2 minuite hop.

Presumably only if they have the space though??
For full price (62.00), you can actually get off and take a wander round, and you have to book that in advance.
Hmmm, I'm very tempted here!