Thanks for the interesting info which is useful to know. I was never too sure about exactly what info was applied to the butt disc; a dealer told me it was the soldier's name and number. Obviously, he didn't have his facts quite right. I do have in my collection a No4 mk2 with fully matching serial numbers which also has a butt disc fitted. But this is a plastic disc with just what I believe to be an armoury number and is placed in a slightly different position on the butt, although on the same side as SMLEs were. This rifle has a PF serial number and is in lovely original condition. This is the only No4 rifle that I have ever seen with a butt disc. Perhaps this was done by a non military organisation such as a private school. Peter how did the army generally armoury number the No4 rifles and where, can you remember, please? Was it like the SLRs, painted by hand with white paint directly on the weapon? Some of the examples that I seem to remember seeing years ago looked as if they were painted on by a 2 year old.