HMHS stands for His Majesty's Hospital Ship. HMHS Delta had been a P&O ship that was requisitioned for hospital. It was painted white and you can see the large Red Cross symbols on the side to deter German U-boats from attacking it. It had served in the Dardanelles Campaign before Dr Glover joins the ship in the Indian Ocean to serve alongside the East African Campaign. It was staffed by 6 Medical Officers, 12 Nurses and 45 other staff it was fitted with 287 cots and 210 berths. When the war was completed it returned to its pre war designation as SS Delta and helped repatriate Australian troops from Plymouth to Albany in 1919. She was scrapped in 1929. From the sequencing of the photographs it appears that this photograph is from 1917.