Thanks for that; sorry if my last post seemed a bit curt; I`ve emailed HMC to clarify the situation and depending on their response I'll contact Nikon - watch this space!
Been reading this thread as I'm considering buying one (even more having read this) - and as I'm in the know re Customs at import - here's my view.
The scope & eyepiece are two separate elements.
Your personal allowance at importation is £145 per each person.
(Note that once an item is over that then Duty (if applicable) and VAT is payable on the whole amount.)
If a couple were to declare these items then generally Customs would not be bothered to charge the Duty & VAT as they would be (if at all) only slightly over that allowance. One person with both - that's a little further over the line. But they will err on the side of generosity.
Certainly declared items of around £150-£200 are not generally considered worth the calculation. (This does not mean that the next time you bring it back from abroad that you could not be charged by Customs at another airport/port - a small risk!)
(If you were to be stopped in the Green Channel and over your allowance - it is
possible you could be charged the Duty/VAT - PLUS a restoration fee for the seized items)
I hope you can read between the lines here.
Also note that any item bought abroad which incurs/should have incurred
these taxes is not necessarily insurable - insurance companies have been known not to pay out for lost items which haven't got Customs' receipts!
Nikon's attitude to "grey imports" I reason has more to do with their dislike of people getting their stuff cheaply.
So a few risks to consider on your savings. If I were off Stateside in the near future I'd seriously consider buying one there - and consider declaring it as two items between two people.