[Marsel]

Thank you MAfan.
That's more or less what I thought, however the book I referred to was very clear that any descendant of the late Electress (without exceptions or restrictions) would automatically qualify, which I didn't find very plausible.
This just adds to a number of other inaccuracies in the book, mind you.

I assume that by "Protestant" faith, they don't exclusively mean the "Church of England" and other Protestant Churches would be fine as well.