Investigators are " 90 per cent certain " the blaze which tore through the Triumph factory was caused by leaking petrol. But they are still trying to discover where the leak actually came from.
They helped us recreate what probably happened on that fateful Friday night.
Once bikes reach the end of the assembly line (1), they are fuelled and then tested on the dyno before the petrol is emptied.
The whole assembly area (2) was immediately engulfed in flames. If anyone had been in the area at the time, they would have died. The fire spread so fast that there was no time for the automatic fire doors, which are designed to contain the blaze, to close.
First it spread to the stores (3), where parts are kept ready for assembly, and then to recently-built workshops at the rear (4).
Fortunately, the nearby paintshop (5) escaped the flames. This area contains highly flammable liquids, and if those had gone up, it would have been far worse.
People near the scene reported the sound of fuel tanks on bikes exploding, saying they were " like grenades going off " .
Around 100 bikes – those built on Friday March 15, the day of the fire – would have been waiting to go out. Though they had been drained of fuel, the tanks were still full of vapour. Fire alarms went off and maintenance staff working at the far end of the factory alerted
the fire brigade. Hazardous materials burning within the building – such as magnesium, aluminium, foam and rubber – made it difficult for firefighters to see enough to tackle the blaze.
Within five hours they had it under control and the investigation began.