"ZONEFACE - why so mean? I read the whole thread now and before. There's no explicit mention of cast. Seemed a fair question."
I guess we may need to work on those reading skills then because, well, let's Review, MargoChanning said about 11 hours before your post,
"Nick Hytner directed (as he did with Bennett's earlier "Madness of King George") and they used the entire original cast, which is currently on Broadway"
That looks to me like an explicit mention of the cast.
when ducks grow thumbs then maybe my opinion will change.