The four medals you have here are, from left to right, the 1939-1945 Star, the Burma Star, the 1939-1945 War Medal, and the Territorial Efficiency Medal. The 1939-1945 Star was awarded to any officer or enlisted man who served for 180 days in an operational command (or 60 days for parachutists and pilots). However, anyone in Burma who served during the initial Japanese invasion in 1942 was eligible for this medal, even if they hadn't reached the 180 day threshold. The Burma Star was granted for any service in Burma or Bengal, as well as to those who served in the Malaya Campaign or in Hong Kong. The 1939-45 War Medal was simply awarded to anyone who served in the military or Merchant Navy for 28 days during the period. The Efficiency Medal was awarded to enlisted men who served a twelve year term in the British reserves, either in the Territorial Army or the Militia. It was also also possible for officers to receive the medal had they been a member of the TA called up in 1939, and promoted to officer during the war. Because your grandad's medal has the 'Territorial' scroll bar, it's clear that he served in the Territorial Army. As a result, he might not have served a full twelve-year term, as war service counted double.