First point to make before even beginning is that there is a disagreement among citizens in the area over the name of the City and the County.
The historical name was Derry (Doire in Irish, meaning Oak wood). In 1613 London was added by James VI/I in return for money from London livery companies for its development.
I use “Derry” as the city and “Londonderry” as the county, mainly so that they can be told apart. Thus the use of the county name in the title is deliberate as Kilkie family members come from inside the city and in the countryside around it.
Derry is the second biggest city in Northern Ireland and the 4th biggest city in the whole of Ireland. The original walled city still exists on the west side of the river Foyle but the modern city expands around the old walls and expands on both sides of the city. In general Kilkie family members lived outside the walls on the eastern side of the river.
Notice from the map that modern Derry is on both sides of the River Foyle, but if you look closely the historical walled city is on the western side.
To be politically correct the BBC always says “Derry/Londonderry” for the city although the name has officially changed.