Complex sentence: Merthyr Tydfil became a local government district in the administrative county of Mid Glamorgan at that time, although it reverted to a county borough again on 1st April 1996.
Split into simpler sentences: Merthyr Tydfil became a local government district in the administrative county of Mid Glamorgan at that time. It reverted to a county borough again on 1st April 1996.