I'm a member of U3A, and tried them first, but I've had no response, which is why I tried the Forum. I used to be a member of Sheffield Experimental Theatre Group, but that was twenty years ago, and they no longer exist. Still, I appreciate your suggestion.
I'd like to form a theatre group for retired and/or semi retired people in Sheffield, and initially I'm trying to find out if enough people would be interested in joining such a group. Although there are lots of companies in Sheffield, they don't cater specifically for this age range. I'd welcome any suggestions on how to explore the possibility.