Just a point about Nieupoort, it is quite close to Dunkirk. Dunkirk was not liberated at this time. In fact it was held by the Germans until the end of the war. I have investigated other allied crashes of planes that strayed over these bypassed ports such as Dunkirk and were shot down. I am not saying that happened here, in fact this link says the plane was on a resupply mission:
https://aviation-safety.net/database...id=19440921-30
but might be a possibility which could explain how a plane could "stray" over occupied territory and crash far away from what we think were the then current "front lines".