Oh my gosh, thank you so much for all this help.
The most important thing to me is that this confirms Jeremiah and Celia, I've never been convinced that they were the right couple, don't why just a feeling.
Sarah was the sister of my direct ancestor John SCALES. I've got both Jeremiah and Celia's parents and I'm sure they are right.
George and Sarah's children were Celia, George, Charles, Mary Ann, James and David. Apparently James and Charles died c1844 in Suffolk, England (I need to follow that up and check). The other children all died, as adults, in NSW.
I wonder if the birth of David to George and Sarah in 1855 could be the child of George Jnr - George married a Jane, not Sarah.