When the SMLE was adopted by the British, it was to be the new universal rifle for all branches of service, including the Royal Navy. This suited the Navy just fine; they like the features of the new design. However, the Army quickly moved to update their rifles for the new MkVII Spitzer ammunition, and this was an issue. The Navy still had substantial stockpiles of the older round-nose MkVI cartridge, and did not go through it nearly as quickly as the Army. The Navy did not want to simply throw out their ammunition, but the differences in trajectory between the two types of ammunition was substantial. So the Navy opted to adopt its own unique rifle variation, the MkI**. This in effect was the new Army pattern rifle, but with the rear sight still calibrated for the trajectory of MkVI ammunition.
This pattern was first adopted in 1908, using rifles with the then-standard split charger guide. When the fixed charger bridge was adopted, the Navy (which still had plenty of MkVI ammunition) chose to update its MkI** rifles to fixed charger bridges, without making any change to their designation. Once they finally ran out of the older ammunition during World War One, the rifles were updated once again to what was then the standard MkI*** pattern. As a result, intact MkI** rifles – especially ones with the split charger guide – are extremely rare to find today. Many thanks to the owner of these two specimens for giving me access to share them with you!