1917 king George sixpence wording Imp

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Can anyone put some light on this coin?What's the significance of the "Imp" impression and it also appears to have a black enamel. Might be wrong though.

The photos suggest that Imp was engraved rather than punched:

→ cursive writing (+ m and p attached);
→ no sign of damage on the reverse, which one would expect if it had been punched.

As for the meaning... difficult to say. The first thing that comes to mind is that it repeats the title of Emperor of India (on the reverse: IND: IMP:), but what would be the point of engraving that? Usually, cursive inscriptions are found on "love tokens" or what I would call "birthday tokens". See some engravings here:

https://picclick.ca/Coins-Paper-Money/?q=engraved

I don't think it will ever be possible to know for sure why Imp was engraved on your coin.