I received an unusual (for me, at least) communication from eBay today. In short: 'The item in question has been classified as restricted. This could be due to import/delivery restrictions or eligibility requirements within the Global Shipping Programme. The item will not be sent on to its final destination and will not be returned to you.
Don’t worry! Your buyer will be notified and refunded automatically by eBay within 72 hours. You will retain the buyer’s original payment. At this time, the transaction is considered complete and no further action is needed.'
So one of the half dozen remaining first ever issued WW1 German gas masks is now residing in an Italian customs trash can, and neither I, nor the purchaser (the world authority on such items) can do anything about it. Sad.