David Cameron? It's perhaps fair to say he called the referendum expecting to win, continue his political career and quell the infighting within the Tory party and achieved none of those.
While Madrid's handling of the more recent Catalan independence campaign has been pretty inept the Brexit vote sets a pretty strong counterexample to "just call a referendum, you'll win, it'll be over for 20 years". Scottish independence is a good example too, that's hardly gone quiet...
