It means:
Educational institutions are the executive bodies of the British Ministry of Education, responsible for the management and training of in-service teachers and new teachers, as well as the supervision of teaching. The Department was established on April 20 1 year 12, replacing the British School Training and Development Agency and belonging to the English Teaching Association.
This teaching institution should be the current international name, because there is no other name for this institution on Wikipedia. In addition, you can see that the international name of this institution used to be the School Training and Development Agency (TDA), which is also the School Training and Development Agency.
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