Curly when the whole story with PC broke and Diana was working at the nursery, she said later that a lot of people didn't realize she only worked there three days a week and the other two she was caring for a little American boy called Patrick.
I have also seen an interview with Patrick's mum who said when Diana came and told her in confidence she was dating a Prince she assumed it was Andrew because they were closer in age and was very surprised that it was Charles!
When C & D went to Washington D.C. to meet Reagan on the trip when she danced with John Travolta, Diana asked to meet Patrick and his family who had moved back to the USA and they were brought in especially.
It sounds like the American family were always very discreet.