There have always been security problems for monarchs and members of royal families...they are a magnet for assassins, both privately motivated lone individuals and agents of well-organized plots on the part of either revolutionary groups or hostile governments.

Note, for example, that a number of western countries are presently quite clearly attempting to assassinate Muammar Gadhafi by using high tech weapons to kill him (not that I'm saying he's a "royal"...but he is in a somewhat similar hierarchichal position within Lybia...).

It's one of the most dangerous jobs you can have, being a monarch or something similar to a monarch...or just being closely related to one...and it always has been so. In fact, it's probably less dangerous now than it was a couple of hundred years ago.