Hi Balloonatic
Your great grandfather - Arthur Swarbrick, was brother to my great grandmother - Sarah Louisa Swarbrick, who married Robert Seddon.
Arthur and Sarah's parents were Samuel Swarbrick (who was the accountant for the Midland Railway, and then General Manager of the Great Eastern Railway Company in England) and Sarah Fawcett.
Robert Seddon and Sarah Louisa Swarbrick had 3 sons and 1 daughter:- Professor Herbert Robert Seddon (who helped set up the veterinary school in Sydney), Samuel Thomas Seddon, Diamond Seddon, and my grandfather George Hume Seddon, who was a lawyer and became Register General of the land and deeds dept.
I have a little info. on the Swarbrick family if you are interested. Sarah L. left a family tree which I have in my possession. I can post you a copy if you let me have your details.
Jenn