Degrees of Separation

In 1998 I met a woman in London, where we were both living, and we began a relationship. Although domiciled in SE London/NW Kent for much of my life, my mother was born and raised in South Wales in the 1920's and 30's, and we used to visit her side of the family there in the late 50's and 60's. My 1998-2005 partner was also born and raised in South Wales, in the 60's and 70's. Back to 1998, and one weekend my partner invited a friend to stay with us in London, as she was travelling from Cardiff on business. This woman had been my partner's landlady for a short time in the early 90's in Cardiff and they had become friends. During drinks and dinner on the first night of her stay, our guest suddenly asked me if I had a cousin called J*****. I was staggered as I do indeed have a female cousin by that name. It turned out that my partner's friend's childhood back garden backed onto my Aunt and Uncle's back garden, and that the two girls had been friends. I had probably even met her 35 years or so previously.