Hello, thanks for your reply. I had the same thought, but when I spoke with customer service they assured me that it was eligible. It is a framed antique tapestry : https://www.ebay.co.uk/itm/297814768175 

My issue though is that ALL of my items are not showing the GSP as being an option. I've checked using a VPN - if you're buying from the US it just says to contact the seller about shipping.