Ok. The Madrid Agreement, April 14, 1891.
Very difficult and hard topic ...maybe only for me.
All governmental documents have a lot of garbage.:)
The Madrid Agreement was signed in 1891 by nine countries: Belgium, France, Guatemala, Italy, The Netherlands, Portugal, Spain, Switzerland, Tunisia.
And what is about UK trademarks?
Here, The Making of Modern Trade Marks Law, 1860-1880.
If you try to combine these two documents, you'll see, that about that time(+/-1891), UK began to use the same rules of trademarks: to mark the country of origin on the item, not just the city where it was manufactured. In order to protect products against counterfeiting in other countries: US, Russia, etc.