Help with mark on pendant please

Can anyone recognise which country this is from? The mark is vaguely familiar but I don't know where to look next as I've tried the hallmark sites and drawn a blank.

 

That's a British Registry mark so it's no later than 1876.

This will decode it: https://www.925-1000.com/registry.html

 

Ohh thank you @Ownedbybear I didn't read the middle bit as Rd it looked like Ad to me.

 

Certainly looks like a British registry mark... but it's not reading right to me...
That clearly looks like the number "2" in the top circular area but only a Roman numeral should be there. Since it is a metal item, there should be an "I" in that top circle. Weird.

 

I can't make sense of it either.

 

I suspect it's a misstamp. The 2 and the I have been transposed.