There has always been a nationalist Dutch underground. Remember that Pim Van Tuin, a flagrantly gay nationalist conservative (parse that, baby) was due to win national elections before he was assasinated. There is still a stong anti-foreign element in Holland.
Since some of us are not up on Dutch Foreign events, I would like to see a link that repeats this before I take this detail as fact. Maybe I am completely wrong and Van Gogh had a film on this politician and this is confirmed in the movie but until I see something more on this, I don't accept this statement as fact. We do have Freepers from Holland on here, maybe they can comment on this matter.
You are right;
A google search found this.
The spelling at google is Pim Fortuyn.