The plate would have been rejected by the BVA if the positioning & quality were not correct. It does happen, HD is not a simple genetic condition & there are outside influences that can affect the development of the hips. I've had two dogs with high hip scores(unrelated)one had a score of 34:34=68 & the other my current bitch 27:29=56. Neither showed any sign of HD & my dog was sound until the day he died(from Cancer)aged 13. I always keep my dogs in hard dry condition & if there is any hip problems the physical condition actually compensates for the malformation of the joint.

The scrutineers are highly skilled at reading the plate & the vet I use to do my scoring X rays is rarely more than a point or two out if anything & discusses the after care(in the case of poor hips)

What is H stamped ? Do you mean the SV system of hip assessment ?