The Bristol Harbour Railway connected to the main line system at Temple Meads, via a lifting bascule bridge over the northern entrance dock to the basin and a tunnel beneath St Mary Redcliffe.
The cargo had been loaded the previous day at Welsh Back and the Master, Henry Cartwright, was now waiting for strong winds to drop.
Knowing the risk of fire for this flammable cargo, all flames had been banned from around the vessel and it had been kept in the entrance lock, not the main basin, overnight.
'A high wall of flame of appalling fierceness' followed by 'a cloud of smoke of the blackest description', typical of burning naphtha, hurled one of the crew across the harbour to land with a broken leg.
Liquid, burning naphtha floated across the surface of the basin and set fire to the ships there, with flames reaching masthead height.
The lock to the New Cut was blocked at the beginning of World War II to ensure that in case of damage by bombing, the waters of the Floating Harbour could not drain into the river.