A bros hallmark

I have a piece of gold hallmarked A Bros (this would appear to be in a triangular shape - it has a large A centrally with bros on the right hand slope of the A - and may have had Ltd down the right hand side).

It also has a horizontal anchor in a square with another square next to it containing an X. The only other hallmarks are a 9 and .375.

just wondered how old it is and where it came from as I think it may be a bit old as it's been in the family for years.

Thanks for any information