Complex sentence: The comprehensive school is situated on the site of the former estate of Lord Aberdare, the main house, Dyffryn House, was still used by the school until its demolition in the 1990s.
Split into simpler sentences: The comprehensive school is situated on the site of the former estate of Lord Aberdare. The main house, Dyffryn House, was still used by the school until its demolition in the 1990s.