For the very reason you mention, the artisan guns available in London always intrigue me. Are people really that impulsive/impatient that they're not willing to wait? I doubt anyone buying such a weapon doesn't have others at their disposal...
I cannot speak to England, but can offer some observations about the people Ive chatted with here in the USA on just that subject.
Many are afraid of the lack of direct contact between themselves and the gun maker. There is a fear of being unable to communicate their desires, and a fear they would not get the gun they wanted. So they settle for a choice from a more-or-less local re-sellers inventory, that they can return if it doesnt live up to expectations.
A surprising number of people have no concept of proper stock fit, or their own needs in terms of the best stock dimensions for them, personally. Even those who understand the potential importance of a properly fitted stock dont know their needs, or have any intent (or means) of being fitted.
Those are two of the reasons people here in the States are content to buy a Spanish side lock from a re-seller.
Speaking for myself, Id rather buy a used gun than have a new gun made. Ive found I can buy a used gun for a fifth to a tenth of the cost of a nearly identical new gun. It has been relatively cheap to have such a gun restored and re-stocked to my measure with a nice piece of wood Ive acquired and supplied.
Alas, its becoming harder and harder to do that, as the resources in Spain dry up.
