MG mint mark ?

[argento]

Hi All,
Just wondering if anyone has seen this mint mark / trade mark before MG (as per image)
The gold button has been stamped on the side " 1oz troy 9999 fine gold, followed by MG"

I don't have any issues with the item being genuine......just curious to know who or what the MG stands for.

Cheers

 

[nicwinner]

Matthey Garrett
check

http://allengelhard.com/the-collections/johnson-matthey/ag-12-kilo-kilo/

ctrl+F "MG"
cheers

 

[argento]

Matthey Garrett

check
http://allengelhard.com/the-collections/johnson-matthey/ag-12-kilo-kilo/

ctrl+F "MG"

cheers

Thank you kind sir.....