Central No4 Target Sight for No1 and No4 Lee Enfield in 7.62 x 51mm - Australian
Central Sights of Australia was an innovator and competitor to Parker Hale of England - check out the list of patents on the devices front face. They catered for the Australian produced No1 SMLE and produced mounting base version that would either fit No1 or No4 rifles, or both interchangeably - these are avaialble seperatley.
They mounted the sight body on the mounting base with a proprietry vee groove system - the nature of wich made it easy to install, error proof and very rigid.
The No4 model sight was developed to give generous elevation and windage adjustment with 1/4 MOA clicks on a vernier scale for both - the elvation is co marked for yards range for 7.62 x 51mm amunition. They also employed a sliding plate with various diopter diamter holes that was captive to the bridge - this example has the central marked plastic eyepiece attached before it.
This item is on good working condition and would make a sound addition to your Lithgow SMLE - bases are available online - I will list options here when available.