Hi, Keith, I am very interested in your concerns and your possible reasons. I have looked at the decanter again, baring in mind your concerns. The scalloped rim and base area should have a gilt gold line around the top. These are very worn in places. The base rim shows clear signs of ware in some areas. The base area is not flat and sits very unevenly. This may not be clearly visible on pictures taken. The gilt pattern designs around the bowl of the decanter also show signs of ware or usage by handling. Please note, this is not to attempt to deter you from your reasons, however, just to provide you with more information.
Whilst on the subject and still trying to find out more about this decanter, I came across this one. I am not sure if the stopper is the right one for this though. If it is the right stopper I'm assuming the price is right too?:
Comparing it to the one on Ebay, there are slight similarities apart from the overall thickness, handle and base design. The handle on mine looks like a fish or snake and on both sides lower down the handle there is, what appears to be prominent round eyes or could this be a mark of helping in identification?
I have included a further picture with the inscribed numbers that was not clearly shown on my initial pictures. I hope this will be of some help to you.