So this is the shipping container that had been red-flagged and set aside.
Grimsby Port had to be completely evacuated. When the hazardous materials and bomb squads agreed they could open the door, this is what they found:
48,000 spools of four-ply waxed slate grey thread, to be exact. The cost of shutting down Grimsby Port for two days was estimated to be in the high seven-figures.
Meanwhile, in Lowestofte Port, an identical container with identical contents passed through customs without remark; so much so that the final destination and purchaser of the container were forever lost in the paperwork. The fate of the container, and its contents, remains a mystery.