Indeed, I find myself wondering just how it was that Susan had access to these goods.
Same as me Mum.
"Overpaid, Oversexed, and Over here."
And as Mum, who was four years older and lived through the Blitz, used to add, "Thank God for that", though I'm not sure which part she was referring to - Mum was a bit of a goer in her younger days.- and all three of my dad's sisters ended up as Yankee war brides.
As well this was in 1945-49, when Susan would have been 17-21, and while rationing would have been in place, it would have eased somewhat with plenty of workarounds for an especially beautiful middle-class (British usage) girl to get them.
**Reading this book a few years ago made quite an impression on me and suggested to me why there might be so much emphasis on the pleasures of the table (which well-fed Americans and Britons today have objected to) in The Lord of the Rings. There's nothing like having a scrappy and sparse diet -- even if you're a don with a family -- to make you remember fondly times when there was a relative plenty of good-tasting food available. Tolkien wrote the book shortly before the war broke out and during the war years, and completed it during the Austerity era; in 1951, when Kynaston ends his account, Tolkien was (as I recall) despairing of seeing new his book into print. In other words, LOTR was written almost entirely during a very long period of dreary food rationing and shortages (also unavailability of other consumer goods, too).
And the Narnia books were written with that memory fresh in mind- there is a specific reference at the end of "The Silver Chair":
And not wretched sausages half full of bread and soya bean either, but real meaty, spicy ones, fat and piping hot and burst and just the tiniest bit burnt.
The Narnia books are full of references to food- an interesting example of Lewis' viewpoint is in a letter quoted in A.N. Wilson's (admittedly not very good) biography , when during the post-war rationing period Lewis writes that he could actually go hungry, and how totally astonished he is that this could have happened to someone in modern Britain.
This after having lived through the Great Depression when malnutrition was a chronic cndition of the working classes. especially in the North, and starvation was not unknown.
But much more on that later in my upcoming thread "Dwarfs, The Last Battle, Lewis, and the Labour government 1945-1951".