A by-election was held for the New South Wales Legislative Assembly electorate of Cumberland South Riding in November 1856 because the Qualifications Committee declared the August by-election which returned Ryan Brenan was invalid as no poll had been conducted at Canterbury.
Brenan was persuaded not to stand to allow Stuart Donaldson to regain a seat, having lost Sydney Hamlets in a ministerial by-election.
[1] A committee had been formed to secure the return of Augustus Morris,[2] however it is unclear as to why he was not nominated.