OBE means Order of the British Empire
King George V wanted to be able to honour the thousands of people who helped to win the First World War, but were not soldiers. These days people who have made rewarding contributions to the arts and sciences, work with charitable and welfare organisations, and public service outside the Civil Service can be rewarded an OBE.
People receiving an OBE may call themselves ‘Sir’ (male) or ‘Dame’ (female). If the person is not a citizen of a country where the Queen is Head of State, the award is called honorary, and the holder cannot use the title before their name. For example Terry Wogan became a British citizen and was therefore called Sir Terry Wogan, but Bob Geldof is still Irish, and is not “Sir Bob”. Tennisplayer Andy Murray and runner Mo Farrah are some of the latest people having received an OBE.
Source: Wikipedia