The result is the loss of lubrication as the oil breaks down, causing - in extreme cases - engine seizure.

! BB spoke to Robert Sole, head of the MCA invertebrates department, who told us: "Teredo navalis in spite of its common name of shipworm, is actually a marine bivalve mollusc that normally feeds on wood particles and is deterred by chemicals."

However, he added, this new strain - teredo vegetabilis - is feeding on the vegetable base of engine oil and causing a massive loss of lubricitude.

According to a spokesman for Castrol, the only way of combating this worm is to use copious quantities of Cod Liver Oil in marine engines. "Understandably in my view, teredo vegetabilis has yet to develop a taste for Cod Liver Oil, " said William Anker of Castrol's Marine Engine Anti-Seize unit. "We recommend a Cod Liver Oil/diesel mixture of 1:1 will keep marine diesels safe and in good working order until we can isolate this strain of shipworm."