Stumbled upon this site when trying to find out where we were moving to – our street is here and where you live in London was (probably) also mapped in 1899 by Charles Booth using his ‘Poverty Classification’ – notice the lowest class isn’t just classifed as low class but also “Vicious, semi-criminal.” or less low class, “Chronic want.” 
Charles Booth Online Archive
(Dark blue/black denotes the poorest areas, red the richest.)