Stephen - a suggestion: Don't go into this "royal warrant" thing on this line. It's a rabbit warren and will dilute the excellence and concentration on the history of pin-fires, which you have so ably been documenting. - let's make a separate line.
Example:
Reilly 1884 label.
--By special appointment to his majesty the king of Portugal;
--By letters patent to the King of The Netherlands;
--Special Appointment to the King of Spain:
And you could add the dozens of advertisements for Reilly highlighting from 1868 - 1870 - by "Gunmaker to Napoleon III" such as this 1869 ad (Fournisseurs Brevets):
These gun makers were "carpet-merchants" - businessmen. In the modern world they'd have the logo "organic" all over their merchandise. For instance, what's the difference between "Special Appointment to" and "by Letters Patent" (Fournisseurs Brevets)?
That said, the question of how a UK Royal Warrant was issued is interesting. Why was Reilly excluded? I'm wondering about religion. But we'll leave that to the Reilly research. You have done a fantastic job here on pin-fires - and all of us want to see more.
