"They also made a movie called This is England which straightforwardly depicts young English nationalists"

Not sure who you think "they" are but "This is England" is superb. It deals with a lot of issues, way beyond just nationalism and the like.

Perhaps you would like to fix your gimlet gaze on "A Clockwork Orange" and deliver a further withering critique.

A simple explanation regarding the increase of the number of nationalists within England is the population has increased. QED.