Yep, 'tis a prank. April fools tend not to involve the royal family especially with politics and don't get us started on the eu... Little round up of the other efforts, so far!
Clearly a joke. But the royal family must be panicking. Imagine if we vote out and all the Greeks, Germans and Hungarians etc. had to go home. The palaces would be empty!
Thanks for your help! The Drudge Report linked to it. One wonders if he was fooled, or just passing the joke on. I can't imagine anybody in the royal household would allow themselves to be quoted like that.