From what I've heard from quite a few who have tried to fish Wharncliffe Reservoir, is that they can't get day tickets & can't get down to look at the reservoir as the gate is always locked.
I don't know how true it is, but if it is the case could the owners offer better access & signs to those who want day tickets to fly fish? after all they're going to have to do the same to advertise coarse fishing.
As for Thryburgh could you not get a day ticket & give it a try, also the chap (the Buzzard) who hovered around hot spots talking & being a general pain in the @rse until he forced someone to move out, he did leave a few years ago
Paul