His is best remembered for his role as General Superintendent of Horse Breeding in India and Chief Veterinary Officer to India, for his work on the Indian cattle plagues and for writing manuals on the treatment of horses and livestock, some of which were translated into Hindi and Urdu languages.
James was the son of veterinary surgeon, Herbert Hallen, who worked with the Inniskilling Dragoons, and his wife Matilda.
He started a school for salutris (horse attendants) and castrators at Babugarh in the United Provinces in 1877.
[5] This was in response to Lord Northbrook's policy to breed horses and mules in India rather than import them from Australia and Persia as was the previous practice.
His examination of the outbreak of rinderpest led to the establishment of the Imperial bacteriological laboratory at Mukteshwar under Alfred Lingard.