This PDF document is a history of Queensland Immigration and the Black Ball Line and makes mention of the Netherby.
The Netherby: the types of passengers

This page is a touch bitty as I put together what I have found about the passengers. Many were, in essence, the ten pound poms of the 1860s. Paying for a passage and bringing a trade to help populate the state of Queenland as part of the Queensland Land Assisted Package, in return for land orders. Others were self funded immigrants. All were coming to start a new life.
Data from mariners.records.nsw.gov.au about the types of passengers in the 1800's. The Netherby passengers were classified as "assisted passengers" as part of the Queensland Land Assisted Package.

Examples of Netherby contract tickets. These two are from an earlier voyage not the 1866 one.