It is devoid of any post service proof markings (which would include a Nitro proof). So this arm made its exit from the military without passing through the British gun trade. I say this because a Birmingham or London proof house markings required on ALL firearms sold in the UK for the past couple hundred years, a legal requirement.
The double broad arrow marking denotes "Sold out of British service", so it might have done a tour of duty in another countries military. I would be checking everywhere for any armourer's markings or govt acceptance marks.
Most certainly ex British service. Placed into Dragoon stores in Feb 1896, marked with rack number 196.
Returned to factory for upgrades in 97 and 98. Again suggests British service at that time.
Lee Metfords were obscoleted in Canada and replaced by the Lee Enfield in 1896. The Metfords were returned to Canadian stores and never received the upgrade.
How this one get to where it is now? That is always a bit of a guess. Could have come across with the British garrisons. Could have been a South African replacement from Imperial stores. Could have found its way over from Australian or New Zealand. Detective work.