What is the important part of this address - yew tree cottage clonturk kilashee rd longford county republic Ireland?

The important part of the address is "longford county". This is because it identifies the county in which the address is located. The other parts of the address are not as important because they are not as specific. For example, "yew tree cottage" could be any house in the county, and "clonturk kilashee rd" could be any road in the county.