Complex sentence: The latter train was an HST High Speed Train, driven by 52-year-old Brian Cooper (who was killed in the accident) and comprising eight Mark 3 coaches with a Class 43 diesel power car at each end.
Split into simpler sentences: The latter train was an HST High Speed Train, driven by 52-year-old Brian Cooper, who was killed in the accident. It comprised eight Mark 3 coaches with a Class 43 diesel power car at each end.