Identification of markings on an Old Sheffield mug

This piece has the crown of Sheffeild, Old makers mark, The Lion Rampant for sterling silver in Scotland, and the Crowned harp for sterling silver in Ireland. They are badly worn and hard to identify. Can any one peice have multiple country markings or do I have a forgery?
Silver tankard markings.jpg

What a truly weird set of marks. The maker’s mark is the (London) mark of Nathniel Locke. None of these marks could ever appear with another in a pair, let alone all together. And then you also have the “Old Sheffield Plate” claim which makes a fifth. I really don’t know what you have there; is it even silver? Probably not as it doesn’t have any real indication of being so.

I don’t think I would describe it as a forgery as it is not trying to be something particular - for a forgery the forger would have gone to a bit of trouble to make the marks consistent with each other. I think somebody has just been having a bit of fun.

I have deleted your 2 duplicate queries under “Reading Silver Hallmarks” and “What’s it worth?” as I think that “What is it?” is probably the most appropriate question.