This is a lid possibly from a cosmetic compact case. It was excavated at Bowning, NSW, Australia.
I would appreciate any help with identifying the hallmarks.
The maker's mark appears to be AB with the number 51 as a separate stamp beneath it (second image).
The triangular mark appears to be the Chester city mark and the lion I believe is the Sterling Silver Standard mark (third image)
Is the O or zero with diagonal line a date mark (second image)
Thanks in advance for any assistance.