Complex sentence: In the penultimate game of the 1984-85 season the club had secured promotion to Division Two, thereby mandating the replacement of wooden spectator terracing immediate afterwards, Heginbotham said he thought two flares or smoke bombs had gone off before the fire started.
Split into simpler sentences: In the penultimate game of the 1984-85 season the club had secured promotion to Division Two, thereby mandating the replacement of wooden spectator terracing. Interviewed in the immediate aftermath, Heginbotham said he thought two flares or smoke bombs had gone off before the fire started.