Complex sentence: In 2011 it became the first grammar school in Northern Ireland to enter a period of formal intervention, however in 2013 it exited formal intervention and Elma Lutton was appointed the permanent principal of the school.
Split into simpler sentences: In 2011 it became the first grammar school in Northern Ireland to enter a period of formal intervention. In 2013 it exited formal intervention and Elma Lutton was appointed the permanent principal of the school.