Ancestry announces they have added to their browse file for London Poor Law records, a file they call "London, England, Poor Law Records, 1834-1940". The records are held at the London Metropolitan Archives.
Records were previously available for the boroughs of: Camden, Greenwich, Harringay, Islington, Lambeth, Southwark, Tower Hamlets, Wandsworth, and Westminster
Boroughs added are: Barnet, Chelsea, City of London, Enfield, Hackney, Hammersmith and Fulhan, Hillingdon, Holborn, Hounslow, Kensington and Chelsea, Poplar, and Southwark are added.
Note that Harringay no longer appears. I suspect they are found under Enfield which has mainly Creed Registers surviving.