Hi rosie99.
Many thanks for your answer. I had been looking in departures from the UK. I hadn't known they didn't really start until much later than I was looking at. But I found my family in the FindMy Past - Australia, Inward, Outward and Coastal Passenger Lists, 1828 - 1972. All six of them mother, father and 4 children, age 1 to 7, sailed from London in November 1861 and arrived in Brisbane in April 1862 on sailing ship Clifton. I just cannot begin to imagine what such a journey would have been like. 146 days at sea- the mind boggles!
So thank you for your help. One again RootsChat has proved very helpful.
Regards
Isabel