Danno-
Do you have photos of other interpretations of the crest? It sounds impressive!
Just a couple impressions I picked up from reading the few messages on this topic:
Note that Mica said it was the simplified rendition. It may be a bit too simple in that it has kind of a cartoony feel to it. We know from experience that Alembic will use natural materials to create texture. The result will, without doubt, be impressive.
By Danno's most recent description, it sounds like he is looking for something more realistic. You don't often think majestic when you look at a caricature.
From the too-much-information department:
I'd say my initial identification would have been to say it was an eagle on a goose. Swans are large and impressive creatures in their own right. They typically have a wingspan similar to that of the largest eagles and would outweigh them by as much as 50%. If we're talking about typical adult birds, Ireland as the location would suggest a 10-15 lb Golden Eagle on a 15-25 lb Mute Swan. There's a couple species of swan that migrate through Ireland for parts of the year, the smallest of which (Bewick's) runs to be about the same size as the eagle.
By the way, Golden Eagles disappeared from Ireland about 100 years ago and there has been work going on over the past five years to reintroduce them.
You're probably not looking for that much information or realism, though...
Hope it comes together for you
-Bob