Hi Emma,
My dad earned exactly the same medals. Here are my notes about each one:
1939-45 Star
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Granted for service in operations from 3 September 1939 to 15 August 1945, the date on which active operations against Japan ceased in the Pacific.
Burma Star
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Awarded for active service in Burma from 11 December 1941; service in Bengal or Assam from 1 May 1942 to 31 December 1943; from the parts of Assam or Begal east of Brahmaputra, from 1 January 1944.
Defence Medal
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Awarded for 3 years' service in the United Kingdom between 3 September 1939 and 2 September 1945, or 6 months overseas in a non-operational area subject to aerial attack.
The ribbon has a broad central flame-coloured stripe with green edges each bearing a narrow black stripe. These colours symbolize the enemy air-attacks on 'our green and pleasant land', air attacks being the key to this award. Service to qualify counted from 3 September 1939 to 8 May 1945 in Great Britain; and to forces overseas to the end of hostilities in the Pacific, 15 August 1945.
War Medal 1939-45
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Awarded to personnel of the Armed Forces of the British Commonwealth and civilians such as war correspondents and civil air transport, but excluding the Home Guard. The qualification was 28 days service operational or non-operational between 3 September 1939 and 2 September 1945.
Paul