Feature Article

The Heckington Show Mystery Object

We took this object along to the Heckington Show in 2008 as our annual Mystery Object. Visitors were invited to try and guess what the object was.

The mystery object is the Ground Zero Indicator (GZI) from the Trust's underground Royal Observer Corps monitoring post at Holbeach. The monitoring post is one of many constructed across the country in the 1950s and 60s to monitor nuclear bomb explosions in the event of a nuclear strike.  There were 46 such posts in Lincolnshire sited in clusters to allow the triangulation of plots, and reporting to group headquarters at Fiskerton.  They were manned by volunteers.  The posts were decommissioned in the early 1990s after the end of the Cold War. The Ground Zero Indicator is a unit containing a set of four pinhole cameras facing north, south, east and west. It was designed to record the position of a nuclear detonation.  The four concave interior faces were fitted with special light sensitive papers to register the position and size of the fireball.  It was positioned at the head of the post's entrance shaft. Heritage Lincolnshire has owned and managed the post since 2000 and arranges occasional open days and visits for pre-booked parties.  Keep an eye on our events diary or contact us if you would like to find out more.

The Ground Zero Indicator (GZI) from the Trust's underground Royal Observer Corps monitoring post at Holbeach

 
 
 
The four concave interior faces were fitted with special light sensitive
papers to register the position and size of the nuclear fireball

 
 
Diagram of the Trust's underground Royal Observer Corps monitoring post at Holbeach