John Gardiner Hamilton was the Honorary Treasurer and Civilian Director of the Imperial Yeomanry Hospitals in South Africa. Over a period of two years he devoted the major portion of his time to the financial and business administration of the IY Hospitals. In addition, he made his "palatial mansion and extensive grounds" available for use as a stationary hospital.
In the original list of recommendations Lord Kitchener "put him down for a CMG". When this had to be motivated, Sir Ian Hamilton only mentioned the "mansion" part and the CMG was turned down. However, Georgiana Elizabeth (née Spencer-Churchill), Countess Howe (who had in September 1901 written to Lord Kitchener to recommend Hamilton for an award)again took up his case on 3 December 1902. As a result he was appointed as a Member (4th Class) of the Royal Victorian Order in the supplement to the London Gazette of 20 February 1903.
Once the wheels started moving they turned fast! In the London Gazette of 8 May 1903 Hamilton was appointed as a Knight of Grace of the Order of St John of Jerusalem : his fellow appointees included Sir Arthur Conan Doyle, Surgeon General Alfred Keogh CB and Lt Col William Babtie CMG VC of the RAMC.
Hamilton also took part in post-Boer War matters military : between 1903 and 1905 he was the Commanding Officer of the Witwatersrand Rifles (rank Lt Col).
In addition, he was three times Vice-president of the Transvaal Chamber of Mines before becoming its President in 1910 and again in 1912.
In 1907 he was elected MLA for Springs (Progressive Party) in which capacity he received the Union Medal in 1910.
Hamilton died in 1912.