But, in the first advert pic I posted they directly quote Hillary as "reporting...spontaneously, on the invaluable service rendered him by the IWC Ingenieur on the long and arduous trek across the antarctic to the South Pole.....".
Thank you. I missed that detail, and was referring to the advert further below.
I also found another pic online with members of the Hillary team being presented with International watches in 1956, with different representatives than in the other pic, so perhaps they were presented with two different watches? It's a possibility, I suppose.
At a slight tangent with the International Geophysical Year approaching in 1957 esteemed horological houses were paying attention to this type of polar adventure, so it was quite topical.
Edit: Just for accuracy - I looked up the image sources again and they are from the same newspaper on the same date 01.12.1956 so even though there are different people in the images it is the same occasion, so very likely the same watch being presented.