I heard it again the other day in parliament when watching the DADVSI debates! Some député was saying something like: "nowhere on the territory of France and of Navarre will anyone be able to make private copies".
I believe it comes from around the time when Navarr(e/a) was an independent kingdom and was ruled jointly with France by Henri III (de Navarre).
Believe it or not, I only learnt that the (protestant) King of Navarre was King of France in the 17th century when I saw La Reine Margot years ago. guaranteed to evoke a violent reaction from police is to challenge their right to "define the situation." --- David Graeber citing Marc Cooper
The expression indeed comes from Henry IV as I checked on Wikipedia and saw that the title "King of France and of Navarre" starts with him and indeed stays up to the revolution.
I just find it incredible that it's still used today. You stumble upon it here and there.
I mean it wouldn't even be a valid expression if Navarre was only in France, as that would make it redundant. And since Navarre is not only in France, it makes the expression somewhat imperialistic!
I googled the exact expression "de France et de Navarre" and it returned 228 000 hits:
(a bunch of historical hits) and hits such as...
"list of hotels of France and of Navarre" "librarians of France and of Navarre" "message to islamists of France and of Navarre"
etc etc
Basically it's still used outside of purely historical applications.