I looked up the path of the Gulf Stream after I posted. Prince Edward Island is actually quite warm in the late summer because of the Gulf Stream affect. However, the Labrador current runs south by this place. The Titanic sank not too far from there. ICEBURG DEAD AHEAD!
I think the Scotland Coast also have palm trees because of the Gulf Stream. Of course, like most palm trees, they were planted there.
I read somewhere that the nuts or fruit that grew into the original Irish palms floated up on the gulfstream, washed ashore and rooted there. I would not doubt that folks decided to plant more of them.