Hi,
After consulting with the Curator of European Edged Weapons at the Royal Armouries in Leeds he confirmed what I already surmised i.e. to dismount this sword to determine precisely actual age and place of manufacture would compromise the historical integrity of the piece. I will, as I said, take the sword to a silver expert in the hope that he/she will at least be able to identify the manufacturer of the silver mounts and that may give a smaller time frame within which I can place the sword. This style of sword did not last for very long so it is not as if we could be a century or so out. It is unfortunate, with British silver being so accurately marked, that the answers are so near and yet so far.
Regards,
Norman.