The Greek royal family lives in exile in London. When were they ousted from Greece?

Explanation

The Greek Royal Family came to the throne after the overthrow of modern Greece's first king, Otto, in 1862. The Greeks offered the throne to Prince William of the Danish Glücksburg dynasty and he was crowned King George I in 1863. Members of this family would rule over Greece intermittently until the abolition of the monarchy in 1974, which followed a military coup and a failed counter-coup by King Constantine II, after which he fled to Rome.