Probably the mother bush was mislabeled. I always thought it was FB, but my neighbour bought a WC, and I was puzzled why it seemed to be exactly identical to what I thought was FB. Anyway, I propagated my original bush, while it was still patent protected, without realizing it. I gave my neighbour a bush, that he looked after pretty well, and the bush got to be quite big. I cut down HIS entire bush, and submitted it for cuttings, which rooted easily. WC and Mary Rose are known to be easy to root, and are known to be super hardy, which explains why they do really well here in zone 4b with No protection (they are on their own roots, so they regenerate from the root if the winter is bad). So my hedge is ACTUALLY a mix of Mary Rose (few, reversions), and Winchester Cathedral (mostly). WC is known to frequently revert to MR, and so eventually my hedge will be an attractive mix of pink and white.
We just spent the last evening with members of the horticultural society, and propagated the hedge by layering. We took 38 bushes, and turned them into 138, easily in 1.5 hours, 5 people working.

Growing roses from cuttings is a fine addiction and yours look very healthy. You spoke of rose sports and I have a Moon Shadow that is gorgeous but won't propagate at any method. I finally found a healthy rooting sucker or sport that is growing
well but still small with thin canes but we'll see.
My question for you is, I've kept my roses tall this year five plus because something is eating all the lower leaves, up to two ft, of the tops. It breaks my heart to see empty canes or flowers that were just ready to open totally gone. The backyard is at the base of a mountain covered with trees. In the front of the house all my roses are tall and flourishing .I'm always experimenting and in the kitchen windowsill have the base of a stalk of celery, some carrots and green onions all rooting well and begging to go outside in the dirt. Now if I put these in a large container close to the roses next to the gazebo which are being eaten, would you think the animals would get into the veggies instead of harming my roses. Poisons, systemics,animal be gone junk, electric devices, sour milk and Tabasco, nothing is working. These aren't big animals, just rats under my gazebo which love to thrive on poison and sometimes squirrels and rabbits.

very interesting problem indeed. i do not believe it is a rat or squirrel, but a rabbit is possible, i've seen rabbits "pruning" my bushes in the winter (saves me from doing it in the spring). rats love to get into compost, and they do a fine job of churning it up (again, saving me the trouble). squirrels can eat fruit, like cherries or grapes for instance, but i don't think they particularly like rose foliage. Veggies are far tastier for rabbits than rose leaves, you could even buy some celery, or ask your grocer for discarded veggies to "feed your pet rabbit", although possibly nowadays he might suspect you are just poverty stricken and looking for free food for yourself. Make sure you are well dressed when approaching the grocer, that might do the trick.