People knew that the Earth produced heat—they were well acquainted with the hot conditions in deep mines—and Leclerc thought that perhaps it was cooling from an original, molten state.

Pietro Ferrero, the 48-year-old boss of Ferrero, an Italian confectionery group whose brands include Nutella and Kinder, died in a cycling accident in South Africa.

It emerged that Ferrero, an Italian chocolatier, had decided not to join any potential rival bids for Cadbury.