British Medals - Korea
British and Commonwealth service personnel were eligible for two medals for their service in Korea. One issued by the UK, called the Korea Medal (1950-53) and the UN-issued Korea Medal (1950-53)
The Korea Medal 1950-53 was issued named to the recipient by the UK, or other Commonwealth, Government. The UN Korea Medal was issued by the UN unnamed except those to Canadian recipients
Korea Medal 1950-1953
This medal was sanctioned by King George VI in 1951 but before it was issued the King had died and was succeeded by his daughter Queen Elizabeth II - the medal bears the uncrowned head of the Queen

The Royal Navy, Army and Royal Air Force each had different qualification rules for the Korea Medal:
Royal Navy personnel had to complete 28 days afloat in the operational areas of the Yellow sea and the Sea of Japan, or one or more days of shore duty
Army personnel had to complete a service period of at least one day on the strength of a unit serving in Korea
Royal Air Force personnel had to complete one operational sortie over Korean land or water, service of one or more days on Korean land or service of 28 days afloat in the same areas as mentioned in the Royal Navy requirements
Personnel were also eligible for the medal if they completed a visit of an official nature lasting a minimum of 30 days
Personnel of any service were eligible for the medal if they were unable to meet their service's requirements, due to sickness, wounds or being killed
Those personnel awarded a MID wore a bronze oak leaf on this medal's ribbon
Recipients of the Korea Medal 1950-53 were also awarded the UN Korea Medal, although the reverse situation did not apply
Untied Nations Korea Medal 1950-53

This medal was sanctioned by the United Nations in 1951 and was awarded to all those who served with the UN forces during the Korean War. Various issues were awarded by the appropriate government, the British version being awarded to other Commonwealth service personnel. The basic qualification was one days service in Korea, with a longer period for those on official visits
The medal was also awarded to those who served in Korea after the armistice was signed in 1953
above text from: http://www.btinternet.com/~stephen.stratford/korean_war.htm