taking a different tack to Agaghdowey which I have learnt to be extra cautious about, i went where my geography isnt that good , Tartaraghan civil parish Co Armagh adjoins Co Tyrone on the south west edge of Lough Neagh . Cloncarrish is an alternative spelling for Cloncarris, and Breagh are both mentioned in my first source, they are townlands in the civil parish of Tartaraghan
Repository : Public Record Office for Northern Ireland
PRONI Reference : ARM/5/2/5
Level : Item
Access : Open
Title : Return of the Registered Freeholders of
Dates : 1813-1820
Description : Return of the Registered Freeholders of £20 and 40 shillings. Barony of Oreilland West.
I found 3 Millsop listed
26_34_Millsop_Isaac_Cloncarris_Edward Obre__1814___?
26_35_Millsop_Francis_Cloncarris_Edward Obre__1814___?
27_46_Millsop_Thomas_Breagh_Charles Brownlow__1817___?
For about 1864, there are two indexs for Griffiths valuation
{1}
www.failteromhat.com/griffiths/armagh/tartaraghan.htmMilsop Abraham Cloncarrish Tartaraghan Armagh
Milsop Esau Clonmacash Tartaraghan Armagh
Milsop Jacob Cloncarrish Tartaraghan Armagh
Milsop James Derrykeevan Tartaraghan Armagh
Milsop John Cloncore Tartaraghan Armagh
Milsop Joseph Breagh Tartaraghan Armagh
Milsop William Teagy Tartaraghan Armagh
{2}
www.askaboutireland.ie/griffith-valuation/index. Covering all Ireland
Milsop Abraham Armagh Tartaraghan
Milsop Esau Armagh Tartaraghan
Milsop Francis Armagh Drumcree
Milsop Jacob Armagh Tartaraghan
Milsop James Armagh Tartaraghan
Milsop John Armagh Tartaraghan
Milsop Joseph Armagh Tartaraghan
Milsop Joseph Armagh Tartaraghan
Milsop Thomas Armagh Drumcree
Milsop William Armagh Tartaraghan
then for other spelling
Millsop Moses Armagh Newry{civil parish is south Armagh} Millsop John Tyrone Clonfeacle [civil parish part of Dungannon union}
Tartaraghan civil parish sits on part of Tartaraghan Road, the later is on Google its about 3 miles plus north west of Portadown. The Tyrone valuation took place earlier about 1859.
More research is needed, but unlike modern people, the people then didnt move about greatly. If I was wanting any clue to where the family came from in Ireland, I would be picking Tartaraghan civil parish, and then finding any surviving church records.
As regards where did they come from I read thru
http://www.houseofnames.com/millsopps-family-crest?a=54323-224. Which suggests middle England around Bucks etc and also a possible occupational name Milksop, someone who knows about milk and whey. Could they have been brought to Ireland by the local landlord, eg the Brownlows or the Obre, etc.
Surprisingly the name is not in the The Oxford Names Companion.
Finally did I miss something obvious about the size of the population with the variant name spellings in Ireland, I came to the conclusion it was relatively rare.
Anyway good luck on your search.