Just waiting for the dust to settle and people to make their best guesses. B-noser nailed it. It is indeed likely to be one of the four variations trialed at Currah in 1900.
The nose cap wears EFD logo which dates it post 1897. No clearing rod hole which dates it post 1899.
The production carbines used a barleycorn front sight. You will note the the one shown by the OP has a post front sight insert similar to that of an Sht.LE. (something I wanted to try).
The rear sight is a modified standard production unit. The Deep V notch (a la Mk.I* Lee metford) has been made by hand by the armourer.
I can imagine an armourer of the day behind the firing line with his tools, filing the sight and then handing it off to a firing line assistant to give to the shooter for re-testing.
The rest of the rifle looks to be untouched. Leave it that way.
On the Nock's form right hand side reinforce, there is a BR (Birmingham Repair) inspector's stamp, which suggests to me that the barrel has been removed and worked on for whatever reason (modified front ramp?).
One more note, not sure if it is relevant. The barrel length on trials carbines was 1/4 inch longer than production units at 21 inches. Moot point as the last trails carbines were made in 1893. This is not a trials carbine, it is a standard ex-service weapon with modifications.
Top ones are the two variations of 1892 pattern trials carbines. Bottom is early production Mk.I.
So you have an interesting piece that has a time and place in Enfield history. Rare, yes. Interesting, yes. Valuable, to the right collector, could be!