[Revel]

Well for me the term “Lot” in this context would mean more than one. Because if you are referring to only one person then why not just say “You”. Neither “You Lot” or “You all” make any sense in the singular form because they are redundant words. To me it is like hearing someone say “You ain’t never”. It sounds just as bad as using double negatives.

[Jamestown1630]

Nopardons explained it correctly when she likened it to 'your ilk'.

From Merriam Webster:

"The Old English pronoun ilca is the predecessor of the modern noun ilk, but by way of a pronoun ilk that does not exist in most dialects of modern English.

That ilk is synonymous with same, and persists in Scots where it's used in the phrase of that ilk, meaning "of the same place, territorial designation, or name." It is used chiefly in reference to the names of land-owning families and their eponymous estates, as in "the Guthries of that ilk," which means "the Guthries of Guthrie."

Centuries ago a misunderstanding arose concerning the Scots phrase: it was interpreted as meaning "of that kind or sort," a usage that found its way into modern English. Ilk has been established in English with its current meaning and part of speech since the late 18th century."