Oxytropis jacquinii Mountain Milk-vetch
At first I thought this might be Oxytropis halleri (Purple Oxytropis) but these were more blue/ mauve than the rich purple we see on the UK plants. This plant was also once known as Astragalus montanus and is found in the Jura mountains of France as well as the Alps. O. jacquinii is a plant only found in the hills and usually between 5,000 and 9,500 feet.