Old SAXON Horn and Brass Vin Tag

I am trying to idenify this Saxon horn as well as the solid Brass tag that is attached to it.

The brass tag attached to the horn, I believe is an old vin tag of some sort, but the person who attached it to the horn looks like they were trying to use it as a mounting bracket for the horn.

The tag has the following numbers listed on it in this format;

0 M C ? G 5 4 1

Eight characters total, not sure if the first one is a letter o or a zero.

I also cannot read the 4th character of the sequence.

The vin or id tag has four holes in it, and I am pretty certain it's not original to the horn, as no combination of any two mounting holes line up with the holes on the horn itself.

I will try to post a better picture of the vin tag once I remove it from the horn.

Thanks!