Letter: Sinking feeling

Sir: The unfortunate Camborne House at Heathrow, now sinking into a large hole in the ground, was named with considerable prescience.

As most Cornishmen know, the town of Camborne is built on a honeycomb of 19th-century tin and copper mine workings. In past years it has been not uncommon there for large holes to reveal themselves without warning, and even for buildings to disappear into them.

Yours faithfully, MICHAEL CLEMENS Hurstpierpoint, West Sussex 25 October