...if they weren't also going to invite Blair and Brown? Surely it should be all former PMs or none?
Yes, it's their wedding, and of course, there's an argument that they should be able to invite whoever they like. But in my view, if they choose to accept the trappings of royalty, along with the wealth and status that royalty confers, then they need to accept that this is not "just" their wedding, it is a state occasion.
Personally, I don't think they should be allowed to make such blatant political statements, and I'm amazed that this has been allowed to happen! AIBU?