quote.............."It is done with ceramics, jewellery , furniture and books etc. throughout the Antiques Trade." Unfortunately, the antiques trade in general, is not known for it's transparence or honesty - they're in business to make money - which doesn't mean there aren't some honest dealers, but they are few and far between.
The matter at heart is whether or not you are destroying the integrity and originality of the article in question, and it's hard to find fault with the proposal that if you can't tell the difference between a restored/repaired piece and a perfect original, then where's the problem. However, I'd take exception to the fact that Emmi includes books.........current thinking is that because of the material and nature of these things, then it's best to leave well alone - isolate the object into a box or whatever, and reduce deterioration to a minimum. Unfortunately, there is a feeling that conservationists go too far with this ethos, and then because of their fragility, these things then remain out of bounds to most of us. The original construction of books has sometimes been quite complex, and it really is fair comment to say that will nilly rebinding would obviously destroy much of the evolution of a books life. But I'd agree that if it's undetectable on glass, ceramics, and jewellery, and provided it's not the Portland Vase, it shouldn't be a problem.
There is probably a difference here as to whether we are speaking of museum property or material in the commercial world. I doubt that the V. & A. would start sticking bits back on, or filing chipped edges - but a dealer would if they thought it would make extra bucks, and remain undetected........... and anyway, don't collectors want pieces that look perfect