Hi
I am a Bruton living in Ireland of Dublin ancestors as far back as we can trace by church records to the mid 1800's living in the old market area of Dublin called Smithfield.Most Brutons in Dublin seemed to reside in this part of Dublin. (the parish of St Pauls Arran Quay and St Michans for anyone doing Church Record research) Some of them were cattle drivers and maybe came originally from County Meath or County Kildare taking cattle into market in Dublin. Coincidently the former Prime Minister of Ireland ,John Brutons father, Joe(Matthew Joesph) was born in this area before moving back to Dunboyne ,County Meath where they originated from.
We never had any anecdotal info on where the Brutons originally came from though it might not all be from the one family as there are many variations of the name in Irish records(Brutton, Brereton,Brewton etc,). It has often been termed as a Norman name which came to Ireland either with the Norman invasion of 1170( a version of the name in France "Breton" where the Normans came from?.) or latterally in the plantation or Catholics seeking refuge in Ireland ,maybe it came from the Bruton town in Sommerset in England which might also have similar Norman origins as the Doomsday book(1086) suggests.
This loosely ties in with the D'Arcy lord on whose estate the Brutonstown sub-estate is mentioned in your research as his is a Norman name. D'Arcy if he was a leading lord in the 1170 invasion might have granted land to a Bruton(Breton) who came over from Normandy/Brittany with him to fight. Might be impossible to find any old papers to verify any of this, even if some rolled up parchment actually exists anywhere!!
We'll keep searching.