A 1915 outbreak of swine fever gives clues as to where the piggeries were. See London Gazette which mentions the same piggeries as this notice by Surrey County Council:

This notice mentions five piggeries in Mitcham affected by swine fever:

1. Westfield Farm, Western Road, in the occupation of John Cornwall
2. Seale’s Piggeries, off Lewis Road
3. Reader’s Piggeries, off Lewis Road
4. Batsworth Road Allotment Garden
5. Church Road Allotment Garden

Westfield Farm can be found in the 1915 Kelly directory as being just north of Fountain Place on the west side of Western Road.

William Henry Seale, of Orchard Villa, Lewis Road, was bankrupt in 1915.

The location of the Lewis Road piggeries can be obtained from the 1915 Kelly’s Directory, as it describes the properties as from Church Road and after Oakwood and Ashtree Avenues. The 1910 OS Map can be used with an overlay to see theses avenues today and as there are only two properties on Lewis Road in 1910, the piggeries can be identified.

This photo of pigs in the 1950s was taken in Batsworth Road and the tanks in the background are on the W.J. Bush factory.