In Kashgar he met the naturalist Frank Ludlow, and between 1933 and 1938 the two made several expeditions into the Himalayan regions of Tibet and Bhutan, collecting thousands of specimens, many of which were new to science. He joined the Indian Army on the outbreak of the Second World War, serving in Assam. In 1943 he was appointed to lead the British Mission in Lhasa, taking over from Ludlow. The two men undertook further plant hunting expeditions in remote parts of Tibet, with their last expedition to Bhutan in 1949. Many of the specimens collected by Sherriff are held in the Natural History Museum, London. In 1947 he was appointed OBE, and in 1948 was awarded the Royal Horticultural Society's Victoria Medal of Honour. On returning to Britain in 1950, Sherriff bought the estate of Ascreavie in Angus, where he cultivated a collection of Himalayan plants, described as having "outstanding horticultural value". He served on Angus County Council from 1952 to 1966.
