Ireland to Everton, Duffy

[Benn2509]

I'm trying to trace my great great grandparents, all I know is that they moved from Ireland and settled in Everton sometime in the late 1800's. My great grandfathers surname was Duffy, but I believe he changed it to that later in life. I think the original surname was Coogan, but I have no way of verifying this.
Can anyone suggest what I can do, or where to research irish immigrants and changes of name?.
I look forward to any replies.
Regards, Benn.

[Cedas]

You could start by looking for them in 1871 -1891 census - do you have any other family member's names?  Any birth, marriage or death certs to give you a clue.  Everton was very popular with the Irish so you will need a bit more info to move on.

[Benn2509]

Thanks for that Cedas, I'll have an ask around with my cousins, and see if they can come up with any other family names or certificates.
I've just noticed on your profile, your researching 'Street' family in Lancs and cheshire. Do you have any from Oldham area? I have a Bertha Street, born 1906 in middleton.