Huh? BP made the announcement that the meetup occurred. That's all the proof needed. The announcement wouldn't have been made if a meetup did not happen.

There are lots of claims out there right now, with varying degrees of shrillness. Only Harry came. There was no meetup. The kids didn't come. They hired children to play Archie and Lili. She came but was ordered to stay outside while He and the kids had tea with the King. Camilla got into a screaming match with Him. The meetup couldn't have happened because Charles had engagements. Etc., etc., etc. BP said it happened. It happened.