As someone with ancestors from London, and one London ancestor born the year that map was published, I have looked at it and found it very interesting, the street my great gran was born came under the "Comfortable, good ordinary earnings" category.
Her grandfather Thomas Roberts lived in Evelyn Buildings in Holborn, he died in 1889. That came under "Lowest Class, vicious, semi criminal". Yet in 1877 the Roberts lived in a Walworth street which was "middle class, well to do". I know Thomas ran a beer house and when that went under he moved to Holborn and applied for poor relief.
Her grandfather Thomas Roberts lived in Evelyn Buildings in Holborn, he died in 1889. That came under "Lowest Class, vicious, semi criminal". Yet in 1877 the Roberts lived in a Walworth street which was "middle class, well to do". I know Thomas ran a beer house and when that went under he moved to Holborn and applied for poor relief.