Buddhism is the state religion of Bhutan. According to a 2012 report by the Pew Research Center, 74.7% of the country's population practices Buddhism.
Bhutanese Buddhist monk looking out the window of a monastery
A state religion is a religion or creed officially endorsed by a sovereign state. A state with an official religion, while not a secular state, is not necessarily a theocracy. State religions are official or government-sanctioned establishments of a religion, but the state does not need to be under the control of the clergy, nor is the state-sanctioned religion necessarily under the control of the state.
Westminster Abbey is responsible directly to the British monarch. The Church of England is the established church in England.