Simplify the following text for a Grade 9 native English-speaking person.
Original: Childers , though 67 , was an extremely hard-working and He died suddenly of a heart attack in November 1974 , while making a public speech to the Royal College of Physicians in Dublin .
Simplified: However , he died suddenly of a heart attack in November 1974 , while making a public speech to the Royal College of Physicians in Dublin .