I don't agree with 'finally' in the question, the BBC has always been impartial, it is part of their charter.
And this peogramme wasn't an exercise in neutrality, it was an exploration of Nationalist Parties across Europe. For it to be neutral, they would have included the counter arguments to the French National Front, but there was nothing.
It was however an interesting programme on its subject. As a round up of the alt-right and anti EU/€ parties across the continent, it did a good job.
It did however lead to the impression that the EU and €uro are about to collapse, which I suspect is mistaken. True there are anti-Establishment Parties in Germany, and France, but it is unlikely they will have the breakthrough that the programme was predicting.
A good article here by akatya Adler, the BBCs European Editor, about the programme.
http://www.radiotimes.com/news/2017-02-09/bbcs-europe-editor-katya-adler-the-eu-is-flirting-with-the-flames-of-extinction