I am looking for someone I knew in Belgium but lived in Welwyn Garden City, U.K. in 1958. I am also looking for someone I knew in London in 1956. What should I do to find them? Thank you?

Have you tried Googling their names to see if any info shows up? In the U.S., there is a site called anywho.com that gives info from U.S. directories; there might be such a site in Europe. You could see if British libraries have phone directories from the 1950s archived but that would only give you their addresses back then, not now. In any case, I would try going to the largest library near where you live in France and speaking to the reference librarian there if Google turns up no leads.

The Salvation Army in the UK will trace lost friends/relatives for you. Give them all the details you know of the person and they will try to trace them and give them a message to contact you if they want. (They will not give you their contact details)

It worked for us in the past and it won’t cost you anything to at least try.

http://www1.salvationarmy.org.uk/uki/www_uki.nsf

if you know what school they went to try www.friendsreunited.co.uk

@RareDenver I personally would not bother the Salvation Army with tracking down old friends, as the case seems to be here. They are more about reuniting families. Did you use them to find a family member or just an old friend you had lost touch with?

@lillycoyote my mother used them to track down her brother. They will gladly re-unite friends as well as family as far as I know though.