God kveld, Spades and TwiggyTree!
Your question, Spades: I exchanged emails with Archives concerning this topic and they used this reference:
"I checked in the Register of Persons Naturalised before 1948 [Archives Reference: IA 52/26, REPRO 1646 & 1647] and found the following entry.
Breck, Thor Matison [Age] 41 [Born] Skesoken [Nationality] Swedish
Miner, Brighton, Westport. [Date of naturalisation] 30 September 1893 [File number] 1893/2212
We should be able to locate and copy this file for you [Archives Reference: IA 1 18933/2212]."
Does this shed light on the question I mentioned earlier?
Magne