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Thank you all for your helpful answers. You raise good points over the matter.
Bobinwales, as I said, I know of no Kayleigh Evans nearby.
Ummm, yes I can prove who my wife and I are via the usual utility bills, bank cards etc so I can't see a problem there. Besides, we've never asked for our details to be concealed on the electoral roll during 30 of living at this address, so a little research by anyone with any sense should eliminate us.
Barry1010, I've tried Facebook, but I can't pinpoint her. Too many people of the same name, some of who don't seem to have disclosed their location.
TheChair, the envelope fell on my doormat. My initial thought was to run after the postman but he would hardly know the correct address either. I felt I was being helpful not nosey as had I known the person concerned, I would have taken the envelope to her. Bednobs, has made a good point in this respect and I'll continue to open mail bearing my house number in the future bearing in mind that identity theft is rife these days.