From this question, here is a quote from The Adventure of the Solitary Cyclist by Conan Doyle, published in 1903:
The landlord further informed me that there are usually week-end visitors—‘a warm lot, sir’—at the Hall, and especially one gentleman with a red moustache, Mr. Woodley by name,
Lexico says the word 'lot' is derogatory in British English:
informal treated as singular or plural
A particular group or set of people or things.
‘it's just one lot of rich people stealing from another’
‘he will need a second lot of tills to handle the second currency’
1.1 British with adjective A group of a specified kind (used in a derogatory or dismissive way)
‘an inefficient lot, our Council’
The additional examples given by Lexico are predominantly you lot, us lot, that lot, &c., or else are made derogatory by the surrounding sentence.
I am BrE, and understand the Doyle quote to be informal perhaps, but generally jovial and not really derogatory.
I would agree that the dictionary quote, 'an inefficient lot', is derogatory - this I feel is mainly because of the adjective: a pleasant lot, for example is not.
Is this a case of context in each case, or has the expression 'an
adjective lot' become derogatory more recently?
Things that would answer this question:
- A comparison of older and more recent texts either proving or disproving my surmise.
- A reputable authority's opinion on this.