Thank you so much, majm, for your further thoughts and information on Portview House -- both of which are much appreciated. I will certainly have a hunt for the house on google maps and take a peel. Although it's a shame (if hardly surprising) that the original structure has not survived.
Well, my first thought on waking this morning (yes, I've got the genealogy bug bad!) was: could this David E J Davies b1856 entry in Ancestry records actually be a really bad transcription for what should have been Owen E M Davies b1854's entry?!!! Owen jnr was born in November 1854, and with what you've kindly explained to me about babies being registered born up to 18 months before when the register started in March 1856, he certainly could have qualified for being so registered. If this is him, then we are looking at 3 transcription errors here: wrong first name, one wrong middle initial, and wrong year of birth
-- but I guess that's not uniquely unusual, if certainly unfortunate! At any rate, I have ordered a transcript of the full entry (rather wish I'd ordered the original, now), and I will, of course, report back once I receive that -- as well as, of course, offering an amendment to the record on Ancestry, if appropriate.
CELTIC ANNIE