Harry can't bring the kids, it would ruin the entire " I need my tons of security because the UK is such a threat to my family" bit. Doing the Well Child bit isn't an official visit so he has to bring his security. It would also ruin the Sussex propaganda about how Meghan and the kids will never return to the UK. Didn't Harry imply in May that he would never return to the UK because it was such a bay of danger for him also?
Be prepared, Sunday we'll be seeing coverage by the Sussexes marking Diana's death.....