Central Bisley sight.

He often has a lot of Enfield target sights for sale. 

I bought some stuff from him. He's busy so takes time to reply, but I did get the parts after a couple of reminders!

Still very occasionally seen on rifles at Bisley!  

There's a few ways to deal with that, left "as issued" its a very messy sight picture.

You can, in order of degree.

1: File or grind the rear face of the battle sight down & reblue.

2: Remove the rear sight blade, leaving the arm & so on fitted. The single screw is staked in so deal with that first so the screw slot doesn't get boogered.

3: Get a slim style rear sight blade (there are variations, the slimmer the better), then remove the original & store it for replacement later if desired attach the slim inverted so the blade faces DOWN into the wood.

4: Remove the sight arm & blade as a unit.

5: Remove the whole ding dang doodle thing.

6: As (5) but also replace the upper & lower hand-guards with a solid one piece unit, if you can find one.

I went with option 3 as it was a good balance between work required, aesthetic appeal & functionality. Plus the blade & notch are still there just facing in not out. That means you could unscrew the Central & un-flip the open sight in just minutes if you had to for some reason.

So there's no interference with the sight picture when using the target sight. And no confusion by having 3 useable sights in competition; which is not allowed. 

With the .22 SMLE. The target sight is set higher for 50 metres, so the original sight on its lowest setting is not an issue.

On the one with the BSA #9 I did that, & on the Lithy I flipped the slim blade.

Both work, but I prefer the inverted slim blade. its just looks "nicer" to me.

Both ladders have been raised to show the bottom of the blade better, to use I just set the elevation to "2" & the blade disappears from the sighting picture. Its all personal preference but if I was removing the whole thing or the entire ladder I'd feel the "big hole" in the forend would look "off" so I'd go the whole hog with the one piece hand-guard.

Here`s some pics of the sight I acquired,not as shiny as yours shamu, but in really good condition.

As seen in one of the pictures, the patent date is 12-11-35, yet mention of Australia??

I'm afraid I can't help you there.

First reply from Oz.

Your sight is almost certainly calibrated for 74Gr MkVII ball, unlike mine, but if you change anything you're going to the Minutes scale.anyway.

That's a vernier scale, on the right of the elevator (I apologize for asking) can you read / use a Vernier?

 because that's what most users of these go to.