The question remains: Who is whistling in Isles of Wonder?

[Spoomy]

From what I can gather, it was mainly Rick Smith who was behind the two original songs from the night, except for some polishing and signing off on the lyrics to Caliban's Dream by Karl. However, I can't find any hints as to who might be whistling on And I Will Kiss and Caliban's Dream.

I would be chuffed to bits if it was Karl. It was definitely one of the most memorable and enchanting parts from the whole evening. It's still stuck in my head all these months later.

Has anyone come across any clues to this mystery?