Stephen,
Frankly I can not see any reason why the London makers would bother themselves with the 'filing or machining. boring, drilling, reaming' of the component parts of a boxlock. I am sure that if the profit margin allowed, they would polish (int & ext), engrave, black, CH, stock and regulate but I really can't think why they would bother with the raw material. They knew that, if the right supplier was contracted, the metalwork (with or without stock and barrels) would be perfectly good for their purposes and they could take it from there.
If I could take Blanch as an example (although Evans and several other well known names would do just as well) I doubt they bothered to do ANYTHING to their main stock lines. They knew the Birmingham trade very well and could specify whatever they needed. Why have a dog and bark oneself?
I grant you that H&H, Boss (Robertson) and Purdey may have had different criteria but I have yet to see a 'London' BL that is any better that a Westley Richard or William Powell (and some a lot worse!).
I have several 'London' boxlocks and I love them all but the difference between them and a 'Birmingham' BL is non-existent.
ATB Toby
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