Thanks, Hugh and Akira. Hugh - you are right - my backpack was very heavy. I set off on 1st May, in spite of which snow was forecast for the middle of the month - and arrived right on time! So I carried wet weather gear, and cold weather gear; a couple of changes of underwear and socks; minimal toiletries; towel, maps covering my intended route; bivi bag, sleeping-bag and closed-cell sleeping-pad; Pentax 67 body and 4 lenses - 45mm, 75, 105 and 165 - which occupy the same slots as lenses we are familiar with today - 24mm, 35, 50, and 85. There were times when I would have liked a longer lens, but there was no way I could add the Pentax67/300mm/f4 (1.5kg) to my burden. I didn't carry a tripod, but did carry quite a lot of rolls of film - not a lightweight item - and my pack, all up, weighed 38lbs or just over 17kg.
I also carried food for 4-5 days and had marked on my maps any place I passed close enough to a village, country hotel or isolated general store. I used them to stock up my larder. I also managed, on a couple of occasions, to sleep indoors, in a bed, which made a nice change.
It was an adventure, and I loved every moment of it.