In the late 1970s mountaineer Hamish Hamilton, already with the legendary Force 10 tent design behind him, began thinking about sleeping bags.
Being discontented with the bags and clothing he had been using in winter in the Scottish highlands, he became intrigued by how the indigenous people of the Arctic Circle kept warm, utilising animal hide with the fur on the inside. By reversing the hide so that the tips of the fur were in contact with the skin, they found that moisture laden air was able to circulate and escape through the porous hide. Even in heavy rain, and after vigorous exercise, their skin remained dry and safe from freezing as the fur’s properties ensured water was removed quickly from the garment. This interested Hamish as unlike other outdoor designers, Hamish was concerned with comfort from the inside rather than waterproofness from the outside.