Hello again Emily,
My sincere regards to your grandmother, my aunt. I too know little about Capt. Joseph IMD. When I read more about those nominals though it appeared that the IMD was for the treatment of Indian Nationals only. I wonder why? A similar mystery is what the STC were as I found an article implying that they acted in a policing role. I am in the process of gathering as many old photos as possible. I know that they include a picture of Richard Burleigh Lowe Brown and one of Olga in a sari. Also, Charles and Kenneth together in the 1960's.