Why is it that Ruth, Tommy, and Kathy are so emotionally attached to the town of Norfolk? and what is significant about what Ruth says about Norfolk? 

"When we lost something precious, and we'd looked and looked and still couldn't find it, then we didn't have to be completely heartbroken. We still had that last bit of comfort, thinking one day, when we were grown up, and we were free to travel around the country, we could always go and find it again in Norfolk."