Born in London on 19 January 1869, he was the second child and elder son of James Sydney Walton and Eleanor Georgina Louissan, his wife.
Walton was initially educated in Paris, before entering private schools in England, culminating in Charterhouse (1881–84); he went on to study medicine at St Bartholomew's Hospital.
The mission temporarily established its headquarters at Changlo Manor, just outside Gyantse, where Walton took it upon himself to attend to the needs of the local populace, notably performing operations to correct cleft palates, a particularly common affliction in Tibet.
He briefly held the post of Chair of Pathology at King George's Medical College, Lucknow, before reverting to military service in 1915.
ex Pampanini, discovered and collected by Walton at Gyangtse on the British Expedition to Tibet, was named for him by the Scottish botanist James Drummond, curator of the herbarium at the Calcutta Royal Botanic Gardens.