I have seen the CC mark before and it does show as the bi-centenary mark for Birmingham 1973, perversely, I have a signet ring which is almost certainly 1973 9ct gold but it doesn't have the two C's on the anchor! The (stock) ring was engraved with my initials in 1978 (my 21st). I've been told it's a BH Britton and Sons ring (who ceased trading around 73ish). The makers mark is B S in two separate circles, there is no '&' symbol inbetween. The Y letter date symbol is identical to the one in the picture.