Okay, so I've now had email replies from both Kruggerland Ltd and NGC. Kruggerland can indeed act as an agent for sending coins to NGC but their handling fees would, in my opinion, only make it worth while if you were looking to send bullion or similar very high value coins. NGC basically said they dispatch the coins with very low-key descriptions and values so as not to attract took much attention from the tax man. In short then I won't bother with the OPR paperwork as the relatively low value bronze coins I'll be sending won't warrant the hassle. I'll also keep each consignment quite small. However, if anyone out there is looking for an insomnia cure, or indeed wants to send a high value consignment to NGC, then it might be worth having a read through this: http://customs.hmrc.gov.uk/channelsPortalWebApp/channelsPortalWebApp.portal?_nfpb=true&_pageLabel=pageImport_InfoGuides&propertyType=document&id=HMCE_CL_000225