Here's a more recent example:
Q. My 12-year-old son and I braved the snow last week to keep an appointment for him to look at a school. On the much delayed journey back to Paddington I was walking through to the buffet car when I saw two friends of a friend who kindly suggested I fetch my son and come and join them. Having said I would, I immediately regretted it because it meant my son (who boards) and I would not be able to chat together alone. I could not think of a way to backtrack and dragged him through to both of our regrets. How could I have explained that I had changed my mind without causing offense, Mary?
J.N., London W12
A. You could have made a show of going to your son’s carriage and then returning to announce that since he had fallen asleep you had better not leave him to wake up and wonder where on earth you were.