The "1907" is the PATTERN of the thing, the "2/18" the month and year it was made: February of 1918.
The Crown and "G.R." is the Royal Signet: it was made for King George V.
The funny arrowhead indcates Government Property, in particular War Department property.
Several Insectors have applied their own inspection stamps to the thing, so they knew precisely who inspected it when it was made and, later, when it was refurbed.
The "X" is the Test Mark. Every bayonet was tested for hardness as well as for flexibility. You don't want one too hard or it will shatter or snap when used.
That one grip is DEFINITELY a P-'14 grip which has been sanded.
ALL of these markings can be deciphered. It just takes a bit of reading and the determination to pursue it to an end. NO genius involved: just a bit of work.
Even I can do it, so you can, too!
Have fun!
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