The 'problem'-that is if you regard it as a problem is that barrels and actions are totally interchangeable so anything we encounter today may have 2 serial numbers, 1 serial number or----you guessed it, no serial number at all. What fun!!
As a side issue does anyone know when HC became the 'official' importer of HW rifles into the UK? Not that it matters much except for those who think evidence of paying full price for an 'authorised' import is a guarantee of quality and proudly advertise their rifle 'with HC stamp' or similar wording when selling it. Personally I couldn't care less where it originates: condition and specification are all that matter to me. Any maintenance required can be done by anyone with a reasonable knowledge of tools and the warranty is pretty much unnecessary unless the owner is a total novice.