In 1987 one of my brothers had come out from England to stay with me in my digs in Durban. I was a student at that time. Before he left England a friend's father discovered that he was coming to Durban and said that he had met a girl in Durban during the second world war and could my brother find her for him. Her maiden name back then was Molly Smith (name changed to protect Molly Smith - well not really - I just can't remember what her name was - this is almost 20 years ago). He also remembered that her dad worked at a sports shop. Durban's relevant population at that time was about 1 million people.
My brother mentioned this to me in passing having already dismissed the mission as impossible but I wasn't as easily put off by the impossible. I happened to know the owner of the largest sports store in town, the famous King's Sports, then run by Allen King. I gave Allen a call and he laughed at what I was trying to do but did say that if there was anybody who would know it was an elderly lady who had worked for the company for many years and would know that sort of thing. He gave me her work address.
On the way to the beach a few hours later we stopped at her work place and told her our mission. She gave us Molly's married name, address and telephone number. Mission impossible accomplished with minimal effort and outstanding results.