I have done her mother side and has a lot of shred cousins on that side and john is definatley not connected to ann,s mother
Sorry, you might have misunderstood what I was saying. I'm not suggesting that John is related to Ann's mother.
Let's say you've got a DNA match, Person A. You look at Shared Matches to see who they are connected to.
The more identified reference points you have, the more chance you have of identifying who that person is related to.
If Person A comes back as a Shared Match to Ann's mother, or other close maternal relative, they can be safely discarded for the purposes of paternal research.
If Person A comes back as a Shared Match to John, or other identified paternal relative, then their tree can be examined for identifiable people in common with other matches.
If Person A doesn't come back connected to either, then it could be that they are a match too far back to have much DNA in common with Ann's mother or to John, or that they are related via a branch of the family that is not connected with the reference people tested.
Since you are going to have a lot of results that are from the outset unidentifiable in terms of which side of Ann's tree they come from, having a close maternal reference person could help essentially half your results so you can better focus on the ones who might actually assist you.