Some twenty plus years ago, whilst living in Cambridge, my wife and I spent a week on holiday at a hotel in Mundesley, Norfolk. We travelled around the area, sightseeing, and included a day in Norwich where, at one point, we took a coffee break in a restaurant at the top of a department store.
The restaurant was busy and we shared a table with three ladies who were already seated. They were complete strangers to us and they and we carried on quite separate conversations.
We could not help overhearing what one lady was telling the other two about an enjoyable holiday she and her husband had spent in Cornwall that year, including the first names of their hosts and the town of Mevagissey. At this point I begged the lady's pardon and asked if she would confirm the surname of their hosts and their address in Mevagissey, which she did and which proved to be the name and address of my wife's nephew, the only son of her late sister, a nephew she had not seen for perhaps thirty years or more. We had all lived on the edge of London up until about 1966, when we went our separate ways, for reasons of employment, they to Cornwall and we to Cambridge.