Very interesting Martin. The Strathnaver was one of five so-called Strath Sisters, operated by P&O, the others being Strathmore, Strathallan, Stratheden, and Strathaird. I've always had an interest in these ships because my parents cruised to Fiji for their honeymoon aboard Strathaird, in April 1936. When I was old enough to take an interest in such things, my father used to point them out to me when they came in to Sydney after the war.
Below is a photo of the Strathaird after her refit, she originally had three funnels.
Peter.