I'm not sure if this is valid as researched online last year relating to NZ, not Australia as people had mixed with a later vessel, but it was the largest sailing ship in the world in 1858.
The BRITISH EMPIRE. There were 2 ships of this name which brought immigrants to New Zealand, one in 1864 and the second in the 1875 and 1880.
The earlier vessel was reported by the Lyttleton Times as the largest ship to enter its harbour being 2600 tons whilst the later was smaller (and faster) being 1499 tons.
The 1864 'British Empire' was built 1851 in Bristol as the paddle steamer 'Demerara' but wrecked at launch and converted to sail and re-named, becoming the largest sailing ship in the world.
The earlier vessel is described in the right-hand column of White Wings of Trade published 1924:
being miss-digitised in this NZ Archive as arriving Lyttelton September 6th 1884 instead of 1864 (the original book is on ancestry):
http://nzetc.victoria.ac.nz/tm/scholarly/tei-Bre01Whit-t1-body-d12.htmlhttp://bristol.wikia.com/wiki/S.S._Demerarahttp://www.brh.org.uk/site/articles/wrecks-on-the-river-avon/https://en.wikipedia.org/wiki/William_Patterson_ShipbuildersWilliam Patterson Shipbuilders, a major 19th Century shipbuilding company, built the S.S. Great Western, S,S. Great Britain, and the S.S. Demerara.
http://bristol.wikia.com/wiki/William_PattersonThis engraving from the Illustrated London News shows the 'Launch of the Demerara Royal Mail Steam-ship, at Bristol’, 1851.
http://www.brh.org.uk/site/wp-content/uploads/2012/12/demerara-sharp.jpg& there are some 1851 photos on the V&A website if input Demerara
http://collections.vam.ac.uk/ not particularly exciting though