No1 MkIV* .22

[30Three]

Yes, maybe it's at similar elevation. I'll have to have a look at my Lithgow No2 MkIV* to compare. Having two lines on the slide could lead to confusion; although it's fair to say that the 25 yard marks are highly visible on the scale. It will be interesting to see if other's could post what sight they have on the .22's

[Mk VII]

It would depend on what foresight someone had fitted.

[30Three]

Normally I would expect an Armourer to change the foresight height for calibrating zero.
Interested to see where the 25 yard stamp is on other .22 SMLE's