Bit weird if Castle isn't there, head honcho put out a video on the 4th May from Castle who was saying why you need to be there.
At least one person got a free ticket, likely more.
Those at the back of the stalls, if there were enough people there for people to sit at the back of the stalls, can pretend it was full. Because of the overhang from the royal circle you can't tell there is nobody up there. Nearer the front of the stalls it must be pretty eerie in there, looking up to see nobody else in there, except probably some ghosts, who will be weeping.
This is brilliant, and not just for snark value. Those in there will see how empty it is and that could be a deciding factor in them leaving, maybe not straight away, but it's in there.
There is always a slightly embarrassed feeling among the audience when there is a poor turnout for a show. I'm guessing that will happen at a success day as well.
Castle's sister posted that she can't wait to talk to the thousands who will be there today.