I fuck my Gran

It all happened during Easter, the whole family were together for the long weekend. On the Sunday morning we all slept late after I big night out the night before. Then as was usual for us most of them went to walk the holy points of the cross setup on a local hills by some our local churches. Grandma Elizabeth 61 widow wasn't going as she didn't like long walks up hills. I Gordon 18 had twisted ankle and so I stayed behind as well, I was laying in my room reading and thought the thin walls I heard moaning. Thinking Elizabeth was ill, I went see what was wrong and caught her masturbating. She was shocked at getting caught, but seeing I now had a hard on. She said You might as well use that and help us both out. Not having had much success with women, I decided to join her and she gave me a good fucking. After which we showered together and were sitting talking when the rest of the family returned. Elizabeth lives with us full time, as she gave house to brother Jeff for him and his family. It's only me, Elizabeth and my parents at home now, my parents are away a lot of the time running their business. Since Easter Elizabeth has visited me in my bedroom every chance she gets, when my parent are away. I get a fuck at least three times a week. She even spends the night with me, when they are away overnight. We almost got caught by my mother, when came home early because she had her mothers pills that she got the day before in her handbag. On hearing her car pull up I headed back to my room and into bed and Elizabeth put on her dress and nothing else. My mother just gave her the pills and left to return to work. Elizabeth came looking for me and joined me in my bed.