Via the ever-wonderful Boing Boing comes this, an 1898 poverty map from the Charles Booth Online Archive.
'Tis interesting not only for the spatial distribution of poverty - you can see where cabbies got their prejudice of going south of the river - but also for the key. One of the colour codes simply says: Lowest class. Vicious, semi-criminal. Expect a reprint in the Evening Standard soon...