Constructed secretly during the Second World War in response to the Japanese threat, they were intended to house operational headquarters in the event of attack.

The weekend before the military left the estate, fire broke out and the Cracroft Wilson House was burnt to the ground.

Using the archives at the Ministry of Defence, Field discovered references to the caverns in newspaper articles dating from January 1945.

The investigation was assigned to another reporter, Bill Cockram, who contacted the owner of Cashmere House which has been rebuilt following the fire.

[3] The caverns now became the home of a series of ring laser experiments set up by the University of Canterbury's physics department, taking advantage of the extremely stable temperature in the caves.