Thanks for your posting and picture of the BP Cockburn.
I was employed as a deckboy on her sister ship the BP Parmelia in 1963.
I remember those days with a great fondness. Both tugs were in prime condition being only four years old. I believe they were constructed at Evans Deakin in Brisbane in 1959. I don't have any photos but have attached one of the Parmelia I found on the net.