Who told you that a Darne is harder to stock than either a sidelock or a boxlock? In reality, a Darne is just different than stocking either a boxlock or sidelock. Thats all. There is way more to properly stocking a traditional actioned gun than a Darne. A lot more precise inletting to be done on both a boxlock and a sidelock thats for sure.
Ted had his Darne restocked in France basically while he waited for it. That aint happening with either a boxlock or sidelock, even by the very best and fastest stockers in the world.

IMHO, the best stocker on this side of the pond is Paul Hodgins. Hands down. One could argue that Trevallion should be on the list too, although I dont think hes doing any work anymore.
Ive personally stood right next to Paul as hes stocked some of the finest guns in the world. Its amazing to watch and learn from an absolute master of his craft.
One of the toughest challenges Ive seen Paul tackle over the years was the complete stocking of a small bore MacNaughton skeleton action. Unbelievable and it was such a challenge that he vowed never to do another one. He says that a lot btw...I think hed do another if the money was right. He said the same thing about the 3 or 4 Boss o/us that have come to the shop for stocking. He finishes them, cusses em, and then a few months later, another one will show up and hes right back at it. :-).

Theres some other extremely talented stock makers here in the states. No argument there. Theres some guys out there that can produce some very fine work indeed. I just have not seen anyones work that matches the level of skill Paul has. Ive seen some very well stocked guns by some pretty big names in the business that have come though the shop, back in the day, to my eye, the workmanship looked amazing! And then I get schooled on the very minor but at the same time significant details and intricacies that pass by the untrained eye (my eyes mostly). Its remarkable. Im very fortunate to have a friend that allows me (aka tolerates me) to hang out, observe and ask ridiculous questions while hes hacking away at some wood or making something out of metal. Its a real treat.