Thanks paul and Ken
Paul I think you could well be right that it may of had an inkstand which is now missing , quite possibly silver.
Ken it does still have its inkwell liner.
The diameter of the opening for the lid is 1" / 2.5cm the internal diameter for the inkwell is just over 0.5" / 1.5cm.
I would call it more of a lid rather than a stopper.
The engraving is all grey cut not polished.
Thanks for all you help Roy