I think the answer here is that a plain London-made tray, by a now unknown maker and assayed there in 1819, has been up-dated, probably at the request of their customer, by a Sheffield silversmith. The border, and likely the engraving, were likely have been added and I suspect the later Sheffield marks will be found on the border.
The problem is, no K·G/&Co. were registered with the Sheffield Assay Office. However, an earlier entry in the Sheffield registers is that of James Kirkby, Gregory & Co. (J·K/& Co) and I think it likely that your mark may be an un-registered version belonging to that firm. Although, in theory, un-registered marks should not have been used, their use does appear from time to time.
Although uncommon ornate form for a late 18th century George III tray, the second set of London marks looks genuine with maker`s mark destroyed.
It may have entered the market again decades later in 19th century, even engraved at that date (rather common practice by Victorians).
To be honest, I am not familiar with the practice how old stock of silver changed ownership and was resold, retailed.
Regards
Both sets of marks appear to be correct. In theory one would have expected the London marks to have been deleted at the time of the Sheffield assay, but that is not a problem here.
Can you make out any of the letters in the London maker's mark? I think I see an 'S' in the top right corner?
Hi Trev,
With my loupe, it appears that the entire makers mark has been obliterated... the lion passant also has a strikethrough, but the head and date letter are intact.
I did not realize that the 'strange' mark was an actual mark. The lion is so curious looking. I thought it was a fake mark.