Complex sentence: From 1947 to 1978 it was the most powerful office within the government, however after the creation of the executive presidency in 1978 the post of Prime Minister became more or less nominal and functions as a deputy to the President.
Split into simpler sentences: From 1947 to 1978 it was the most powerful office within the government. However, after the creation of the executive presidency in 1978 the post of Prime Minister became more or less nominal and functions as a deputy to the President.