Dawn,
I subscribe to a a couple of genealogy services and one has data on the horse & cattle brands of that era. Virtually anyone whom had horses or cattle would have probably had their own branding symbols for ease of horse/cattle identification if stolen or if they wandered off or where cattle mixed in areas of no fencing. It was likely that George Ironside took out the brand certificate soon after he settled at Eton.
His surname might have also been written as Ironsides under certain records as well.
A George 22 & Eliza 23 Ironside arrived on the "Emperess of the Seas" in 1865.
Gerry