I was flying COA-KOKSY-DVR at 4500' and Ostende APP told me, when I asked about it, that the Koksijde CTR was active up to 3500'. So I could fly overhead at 4500' without any further clearance. (Other than the one I had for the Ostende TMA.)
A very queer story, this, very intriguing to me. Was this during normal EBFN operating hours? Any mention in the notam's? Were you offered any explanation?