This happened about this time two years ago. It was the beginning of our good Irish weather and I was relaxing in my smaller sitting room.
I had just spent the day cleaning and moving my sitting room from the larger room at the back of the house (extension) to the smaller room which was part of the original build and was a lot cooler in the summer.
As previously stated I'd spent the day cleaning and re-arranging the rooms. In the back room I now had my dinning table and chairs and not much else.
After the hard sweating work I went up and got cleaned and changed into clean clothes, I went down stairs into the sitting room and sat on the sofa to relax. Just as I sat down I got a phone call from my younger sister, we were chatting away when suddenly I saw a tall man with dark hair walking down the back room.
I'm going to take a minute to describe the layout. My smaller sitting room is at the back of the original build with the window looking out onto the back garden and the side of the extension where the double glass doors are. During the winter and summer I alternate sitting rooms as the old house is cooler in the summer which is nice but too cold in the winter.
Anyway from where I was sitting on the sofa chatting to my sister on the phone I saw this tall man wearing slacks and braces and a loose white shirt walking down the extension. I said to my sis "oh my god! There's a man in the house!" I ran out while still on the phone to my sister shouting "hello". My sister was giving out to me while I ran out but when I got to the archway between the kitchen and the back room I was gobsmacked to see there was no one there.
Not only was there no one there I realized where I'd seen him walk was where the dining table and chairs where which would be impossible for a live person to walk through. I relayed this to my sister and she just retorted "you are not wise running out to see who it was, ghost or not, it could've been dangerous".
I was so bemused after it that I didn't think much about it for a few weeks when I saw a picture of my grandad when he was younger and it looked just like the man I had seen. Only the thing that's more weird is that my grandad is alive a well to this day.
Any ideas on what this could be are welcome:)