As information on Trials T rifles is a little scarce, it took a while to find this out , however please correct me if i am wrong . Some ( most ? ) trials rifles under went an improvement program. These rifles will have the original date of manufacture over-stamped 1933. At least 3 things have been changed. firstly the bolt was changed for one of a higher grade of steel and as Peter has stated it has a steel batch number . ( Were there different batches ?) Second the rear sight elevation screw was changed from 4 to 6 clicks per turn and then the cocking piece was changed from a side locking cross screw to the standard rear locking screw. I am not aware of any other changes. A couple of years ago i managed to examine a trials rifle a 1931, date not over-stamped , side locking screw on cocking piece and 4 click rear sight screw, no SBN number on the bolt, which had matcing number and Enfield markings, it looked completely original to me. unfortunately original cut off and for-end were gone. Can any one explain the SBN on the bolt, as the bolt/locking design is virtually the same as a No1, the metallurgy should have been sorted out years earlier.
As for my rifle,will remove butt and check for number , and take a few more pics of mount, will post asap but am on mobile broadband and my upload speed is about 30 mins per pic and this is really testing my patience.