Just a quick reply, to let you know I will be in touch with you privately later with the email details of Harry's schoolfriend.
(It's on my old computer).
Ærø - well, the ø (island) - is pronounced as in the French "eu". Or roughly Err-eu (definitely not Aero) ;-)
On the map - well, it's a small island in the Baltic, just north of Germany. You can see the lights of Flensborg from what they call a hill there. More like a hummock, in my scheme of things - but then, Denmark is a very flat country :-)
If you're looking in a map index, you may find Ærøskøbing, which is the main town on the island. A lot of smuggling from there in the C17th - that's what I'm researching at present. Ærø was part of the Slesvig duchies, rather than the Danish kingdom, so it was open slather :-) A beautiful place, too, with all the old houses preserved.