royal malta artillery mess waiter's button??

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For general interest I am posting this Victorian era RMA small (16mm) gilt open backed button, which unconfirmed sources have attributed as possibly being a mess waiter's button.
The RMA was a part of the British Army in its own right, and was included under various Dress Regulations. Normal RA buttons were worn, however Mess Waiters buttons were governed by the regiment itself and so i believe Sealed Patterns are non-existent??
It would be a boon to have this button definitively confirmed and not just attributed

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