I think maybe it was just an unusual theme this month
I didn't even know much about the jubilee holiday days till a couple of weeks before. Also the Johnny Depp trial was being televised! Perhaps a big distraction. Or maybe just some people anti monarchy ha ha.
I think themes are good though as it gives people an idea for photographs and some can still be very simple if props are an issue. Just wondered though if an "ongoing" theme might be an idea? Obviously seasons can be an ongoing theme, but maybe something else? Like a few months of colour themes? (red theme, blue theme, silver theme etc) or a few months of "activity" themes - to include eating, sleeping, wheeling, general play time etc. And maybe one theme a year where photoshop things are allowed - just for fun.