To add to that it was only a few years earlier, 1947 (vs 1953) that NZ ratified the law allowing their further independence from Britain. Wikipedia claims that into the 70s many in NZ considered themselves to be part of a British colony.

Also the expedition was the "British Mount Everest expedition". I think it's fair to include marmalade being in Hillary's supplies as being indicative of British cultural adoration of marmalade. Hillary's grandparents were from Yorkshire, UK.

Apparently Hillary, as his father and brother, was a beekeeper; I wonder if he took honey too.