Complex sentence: The castle was set alight in a nightime raid by the IRA in 1922 and destroyed, the story of which Massereene would often tell after dinners, both private and public, being in the castle with his parents at the time.
Split into simpler sentences: The castle was set alight in a nightime raid by the Irish Republican Army (IRA) in 1922 and destroyed. Massereene was in the castle with his parents at the time.