Hi Lizzie
I have the book 'Is Yours An S.S. Great Britain Family?' as my Manx family Chubbin/Cubbin arrived at Melbourne on it in 1867 on Voyage 30. Then they came on to N Z from there.
I have checked p 93 and there are only 3 Whitaker listed all on voyage 23, 1863. Mrs Hannah, 29, Walter 2 and Maria no age given. So that clears that point up for you.
I'm sure if they had travelled on this ship, family would have talked about it for the rest of their lives - as mine did as the steam voyage was history making and such a change from sailing ships.
The S.S. G.B. is now restored at Bristol, Eng. and I have been on it and aghast as to how small it was.
Only the Salons for the 1st Class had been restored and as my family had travelled out steerage class it would have been interesting to have seen how a family of seven could have been accommodated for the 59 days. I mentioned this to the receptionist as we left saying that a large number of those travelling to Aust/NZ could only have afforded the steerage passage and it would have been interesting to see how they coped, but all I got was a frosty stare! Oh dear! The class system??? I put my foot in it!

My gm was an infant on the trip but her sisters, 3, 5, and 8 remember how kind the sailors were when they lifted them up to see the icebergs floating past. Warming of the earth then maybe!!
Will do Lookups in the book for anyone else - will try to remember to check this post from time to time.

Good luck with your research - Faith Green N Z