3 little stories starting with the least surprising.
Years ago I went by train to London, As I was getting off, I met the son of the then church vicar who was about to board the train.
Years ago I had a phone call from a potential client. The client told me the name of the road he lived in which is a long road just under 2 miles long. We had a discussion and I agreed to meet him at his house. Turned out he lived next door to my parents, He hadn't lived there long so didn't know that.
Years ago I was told by someone at the church that he had been abroad in Hong Kong, On the flight there from either Gatwick or Heathrow he sat next to a stranger. They talked during the journey and it turned out that the curate who had recently left my local church had moved to the church (elsewhere in the county) where the stranger went to.