The Buncefield explosion occurred when a gasoline storage tank overfilled after both its level gauge and independent high-level switch failed. Gasoline vapor formed a massive cloud that ignited, causing significant damage to surrounding business parks. Fortunately, the Sunday morning timing prevented fatalities, though 43 injuries occurred. The incident revealed critical gaps in safety control verification, testing procedures, and maintenance regimes. Twenty years later, the disaster emphasizes the importance of recognizing weak signals, maintaining bund integrity, and ensuring operators actively monitor tank filling operations rather than relying solely on automated systems.