1918 SMLE .22

I recently picked up a very nice 1918 SMLE .22 trainer. It is an SSA peddled scheme rifle that has been rebarrelled in .22
I have not been able to work out the butt disc markings. If anyone can help on that; I would appreciate it.
Attachment 101712Attachment 101711Attachment 101714Attachment 101715

Heres the butt stock disc.
Attachment 101716

This rifle also has a steel butt plate with a gunmetal trap for the oil bottle. According to Skennerton these were by Linley & Co as part of the peddled scheme