English L1A3 bayonet, first model. Unusual marked. (ABCN169)(K511)(JN63-3)

SLR, Semi-automatic rifle L1A1 Cal. 7.62.  First model. Minty parkerized fullered Bowie type blade. First 1. cm blackened.  Unreadable date and maker on the ricasso. Blackened pommel with an Enfield stamp Ð and a /I\. T- type mortise slot. First model crossguard with muzzle ring MRD 14.8 mm. 
Top of the pommel is unusual marked; L1A3 over 0257 
Black sheet metal grips are riveted to the tang by two hollow rivets. Both grips are crisp NATO code marked: 1005999502379 only. 
Minty and correct blackened steel No. 5 MK1 scabbard with round frog stud and a brass throat. No dents.
Comes with its Minty and correct green nylon SLR frog as found. No markings to the frog.

Unusual marked L1A3 bayonet! Never seen before.