Green’s Dictionary of Slang

a second-rate artisian, e.g. tailor or shoemaker; also attrib.

1861		(con. 1840s–50s) H. Mayhew London Labour and London Poor II 366/2: A tailor who ‘whipped the cat’ [...] would occupy a day, at easy labour, at a cost of 1s. 6d. (or less) in money, and the ‘whip-cat’s’ meals, perhaps another 1s. 6d., beer included.
1872		Morpeth Herald 10 Aug. 5/3: To have clothes properly made never employ a ‘whipcat,’ seek a place [...] under proper superintendance.
1877		Northampton Mercury 28 July 7/5: Mr Hilton could not allow any Jews at the grand union [...] a whipcat shoemaker might stay there, [...] or even a peanut vendor, but no Jew.