4392 Private George Sinclair, 5th Dragoon Guards. His discharge papers state "Gun shot wound chest. Received in action at Steikfontein S.A. on 6th June 1901." He was discharged as medically unfit on 19 November 1901. Despite leaving for South Africa on 11 November 1899, he was not with the regiment at Ladysmith, as the medal roll indicates Orange Free State, Transvaal, and Natal clasps only. The 5DG regimental history has nothing for anything near this date so possibly he was serving away from the regiment when this happened.
Thanks for asking that pertinent question!
SAFF shows 5DG had two casualties on 9th June, 1901 (not 6th June); Ptes Sinclair and Hill. At the time of their wounding, Stirling says that 5DG operated in the Western Transvaal and did much work in the Klerksdorp district. So the incident of 9th June 1901 was most likely a clash of patrols or occurred on convoy duty. Perhaps Mike may be able to fill in some more of the background?