He was a progressive doctor who kept abreast of the latest advances in Europe, Britain and the United States and introduced new procedures and techniques into the mainstream of New Zealand medical practice.

[4] At Wairau he introduced the sterilization of surgical equipment in line with the discoveries of Louis Pasteur and Joseph Lister, and performed advance and complicated abdominal operations, including the first recorded appendicectomy in New Zealand.

He also carried out a two stage laparotomy on John Ballance, the Prime Minister of New Zealand, who was mortally ill with chronic bowel obstruction.

He carried out research in neurosurgery and into the presence of uric acid in the body as the cause of disease and followed the investigations of William B. Coley into immunology as a treatment for Cancer.

He was also active in the wider community and helped to establish the Marlborough Cricket Association and Football Club and contributed to the construction of a gymnasium and swimming-baths in the town of Blenheim.

[9] In 1900 Cleghorn was suffering from chronic kidney disease and high blood pressure, and he decided to close his General Practice and return to England for a spell of recuperation and further medical research.