French citizens can take satisfaction that their nationality has once again been ranked as the best in the world, while for citizens of the UK, the ramifications of a ‘hard’ Brexit could well sink the quality of their nationality from eighth globally, to 56th (the current position of China).

This is according to the latest findings of the Kalin and Kochenov's Quality of Nationality Index (QNI), which measures and ranks all the world’s nationalities as legal statuses.

Holding the top spot for eight consecutive years, France earned a score of 83.5 percent out of a possible 100 percent — less than...