Main Setting - correction neededEdit
The story is explicitly set on Laurie Island (which is named in it), during the residence of the Scottish National Antarctic Expedition, not on Antarctica. See the Wikipedia article Laurie Island, especially the 2nd paragraph of the History section. --22.214.171.124talk to me 16:56, January 17, 2020 (UTC)
I referred to the Wikipedia article as background only. The story itself is the source. In my hardback copy, this story runs from p75 to p85 & on p80 there's the following exchange (the Doctor speaks first):
- 'Tell me Mr Cuthbertson - would this be Laurie Island then?'
- I remember putting my hands up to my head, suddenly feeling dizzy at the impossibility of it all. 'Yes, of course. But how did -'
This is an in-universe source explicitly giving Laurie Island as the location.
The "Antarctica 1903" setting is given on p73, before the story begins. By the very rules you cite, that is not a valid source, because it is out of universe (not within a story).