A by-election was held for the New South Wales Legislative Assembly electorate of Cumberland South Riding on 17 October 1856 because William Manning was appointed Attorney-General in the Parker ministry.
|3 October 1856||William Manning was appointed Attorney-General.|
|3 October 1856||Writ of election issued by the Speaker of the Legislative Assembly.|
|14 October 1856||Nominations|
|17 October 1856||Polling day|
|20 October 1856||Return of writ|
|William Manning (elected)||893||80.6|
|Total formal votes||1,108||100.0|
- "Sir William Montagu Manning (1811-1895)". Former Members of the Parliament of New South Wales. Retrieved 13 May 2019.
- "Writ of election: South Riding of Cumberland". New South Wales Government Gazette. No. 152. 4 October 1856. p. 2617. Retrieved 31 August 2020 – via Trove.
- Green, Antony. "October 1856 Cumberland (South Riding) by-election". New South Wales Election Results 1856-2007. Parliament of New South Wales. Retrieved 10 January 2021.