Well, that would be interesting. These type of monument are fairly limited to the Scilly Isles, but 4 do exist in County Waterford. These 'undifferentiated passge tombs'* (as we call 'em over here) were found to contain exactly the same type of grave goods and were dated very closely to the Scilly monuments. Obviously the trip from Scilly to south Ireland is not a big jump.

If the same thing turned up a long way away it would throw a few people.

The Entrance Graves (and undif PTs) are defined by a shortish, straightish passage that simply widens to indicate a chamber. There is often a sill stone at the junction between passage and chamber to give you a helping hand. Examples in Ireland are Matthewstown, Harristown and Carriglong.

*There are other undifferentiated PTs in Ireland as well (at Carrowkeel, Knowth and Loughcrew for instance) but they aren't the same.