Letter: Double, double ...

Sir: I was delighted to see your front-page account (21 December) of the invocation of witchcraft to ensure the safety of Channel Tunnel passengers. With the winter solstice having a four-year cycle "in which the forces of earth, air, fire and water are involved", clearly one cannot be too careful.

This evident allusion to a combination of hydrogen derived from oil out of the earth, nitrogen and oxygen taken from the air, their reaction at glowing red temperatures and passage beneath the sea, is a most evocative reference to the manufacture of ammonium nitrate fertiliser and its transportation through the tunnel.

Is it too much to hope that this positive action for the sake of public safety taken by the witches of the Covenant of Earth Magic be supplemented by the wizards of the Health and Safety Executive casting their own spell, declaring this substance to be classified as explosive and forbidding its continued transportation through the tunnel before a wagon-load gets too close to a fire?

Dr SIDNEY ALFORD

Corsham, Wiltshire