George Lindsay Bonnar senior, son of James Bonnar and his wife Hannah Ferrier, qualified as doctor of medicine (MD) and licentiate of the Royal College of Surgeons of Edinburgh. He was the author of 'A case of neuralgia of the ischiatic nerve' (British Medical Journal, 1857) and 'A critical inquiry regarding superfoetation, with cases' (Edinburgh Medical Journal (1864-1865, in two parts). He arrived in South Africa in August 1870 and was living in Durban when he joined the newly founded Durban Medico-Chirurgical Society in 1872. Although he moved to Greytown around 1873, he remained a member. In 1876 he was appointed to the Durban Medical Centre and by 1880 was practising as a surgeon in West Street. He served as president of the society from about 1882 to 1884.
In 1873 Bonnar was appointed, with veterinarian James W. Winter* and medical doctor P.C. Sutherland*, as a member of the three-person Commission on Redwater. Their "Report of the Commission on Red water", describing among others the pathology of the disease, was published in January the next year in the Natal Government Gazette (Government Notice 32 of 1874). It led to the appointment of Samuel Wiltshire* as the first Colonial Veterinary Surgeon of Natal.
Bonnar senior was married to Jane Walker, with whom he had 5 children. He should not be confused with his son, George Lindsay Bonnar junior, born in Scotland on 1 April 1856. He too studied medicine at the University of Edinburgh, qualifying as master in surgery and a licentiate of the Faculty of Physicians and Surgeons of Glasgow in 1885. He was also a licentiate of the Royal College of Physicians and Surgeons of Edinburgh. He applied for a license to practice in Natal in 1885. In about 1893 he was appointed district vaccinator of Indians in the Isipingo Medical Circle, where he served until at least 1912. In 1896 he was awarded the degree doctor of medicine in Edinburgh. By 1890 he was also practising in Durban, and in 1898 had joined the Natal branch of the British Medical Association. He was still practising in Durban in 1904, but moved to Cape Town before his death in 1926.