Unknown marks on very old silver jug.

[CH4520]

I purchased this jug from a flea-market at redcliff (North of Brisbane, Australia) and can't find any thing about it. I cannot tell if it is silver plate or sterling and making matters worse it would appear a mark has dissapeared. The jug appears to be very old and I can see the prince of wales badge, a gothic A, a shield and the no. 610 but other than that, I'm stranded.
Can Anyone Help?

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