Very best...no taking turns, no books, let the leaders lead and the rest of us sing in the choruses and occasionally ask if someone wants to lead one.

To me that totally misses the point. If that's what you want, you might as well go to a concert. A singaround is about participation and most people go to a singaround expecting to be asked to sing - to take part. There are a few who are happy to listen, but they tend to be the exception.