Nothing about who made the blanks or who originally bored the tubes. I'd assume that in London by 1890, Liege was the source of the blanks and perhaps even the preliminary boring.
What would lead you to assume that? There was a myriad of barrel sources in England during that time at the British gun industries disposal. On higher end guns like Purdeys, Whitworths would’ve been the supplier of tubes….the barrel borer….either in house (yes, Purdeys actually had the personnel and equipment), or any of the barrel bores/specialists in Birmingham, like Ford.
Thomas Kilby, Charles Lancaster, etc we’re renowned barrel makes to the trade.
