Thanks! I found some more information about these helmets and the Bescherming Bevolking in the meantime, thanks to your information. Am I correct that the white helmets indicated the rank of 'blokhoofd'?
Many years ago, a Dutch relative gave me this Brodie helmet. Apparently, it was used in the Dutch East Indies after WW II but I am not sure about this. Can anyone tell me which type of helmet this is? Is it British or American? Why is it painted white? There is a number stamped to the rim (see picture) but it is hard to read. Something like IIVB55??M