RAAF Mother brooch

I have just bought this brooch and wonder if anyone here would know anything about the makers mark?
It was sold as silver tone metal and was quite dirty when it arrived. I gave it a bit of a clean and it was gold tone, not silver. Then I spotted the marks on the back which look to be 9C SIL LD-AL. I understand this to be 9 carat gold & silver - the brooch itself is gold and the pin & C clasp are silver.
I have searched online and can't find any makers with those initials. As this is an Australian Air Force item I wonder if it was made there rather than in the UK. I found a similar RAAF wishbone "mother" brooch in a museum in Melbourne but with no information about the makers.
If anyone could help I would be very grateful.

 

I’d think Australia made. I’ve seen sort of similar marks on Aussie bits.

 

I'd have nabbed that too. I look for WWII sweetheart/mother/homefront jewelry and that's this in spades.

 

Yes, I think it must be. I gather Australia doesn't have standard hallmarks like the UK.
I would really like to track down the makers but have had no success finding anything about LD-AL.

 

I collect these things too - it makes me a bit sad wondering what the story behind each piece was and how it ended up in a charity shop/car boot sale/eBay etc.

 

I agree, the marks are likely Australian.

I suppose wishbones and boomerangs both stand for the wish of a safe return.