The York 37 Post (Brandsby) Restoration Project

In all but a few instances the Monitoring Posts were built to a standard design consisting of an access shaft, a toilet/store and a monitoring room.

The toilet and access shaft are both self explanitory. The monitoring room would be the living and working environment for the three Observers on duty. It housed the beds, rations and personal equipment needed to sustain those inside. It also housed the operational equipment needed to monitor the blast and fall-out from a nuclear explosion.

The Bomb Power Indicator or BPI (sometimes referred to as the Blast Pressure Indicator) works by measuring peak over pressure from a bomb blast. 

The instrument is connected via a pipe through the roof of the monitoring room to a set of metal baffles made up of two 150mm diameter metal plates set 15mm  apart.  

The force of the blast passes through the baffles and forces air down the pipe into a set of brass bellows. The pressure is registered on the dial in kilopascals and remains at the highest point until reset by the Observer.

 The Ground Zero Indicator or GZI is a simple device made up of four pin-hole cameras arranged in a single metal case. The Observers, on taking up the post, would secure the GZI mount to the space left on the top of the access shaft ensuring the holes on the GZI correctly aligned with the four cardinal compass points. They would concrete the mounting in place and theoretically any GZI would correctly align. The Observers would place four pieces of photo-sensitive paper in the GZI in cassettes (basically a clear perspex sheet marked with height and bearings relevant to the compass points) which would then register light, for example the burst of light from a nuclear blast, on to one or more of the sheets. The sheets would be exchanged for new sheets and the exposed paper would be used to determine the size and nature of the bomb. Used in conjunction with the BPI information the exact position of the bomb could be trangulated by Group HQ using information from two or more posts.

The Plessey Dose Rate Meter 82 Fixed (PDRM82F)Fixed Survey Meter or FSM remained in the post and registered the fall-out present outside the post. The Geiger-Muller Tube, on the left, was passed up a second pipe in the monitoring room roof on the end of a telescopic rod and inside a probe cover and connected by a co-axial cable to the FSM. The FSM was powered by three 'C' type batteries and readings were taken every five minutes.

Another version of this instrument, the PDRM82M ('M' for mobile), was virtually the same but did not have the Geiger-Muller Tube and would be worn around the neck of any Observers who happened to venture outside.

The British Telecom 'Teletalk' was a commercially available telephone-based communication system. It maintained an open phone line on a dedicated circuit in a similar way to an intercom. The posts in a cluster could talk amongst themselves and hear all conversation within the cluster, but could also communicate directly with Group HQ. Strict voice procedures would be adhered to.

 The personal Dosimeter was worn by all personnel. It detected radiation present in the air and served as a warning to the carrier.

When placed in the charger the Dosimeter could be 'zeroed' or reset in order to maintain an accurate reading. 

The toilet/store. Self explantitory really! Shown here are the 'Elsan' chemical closet, the spade, brush and, behind the closet, the pick. The crate is for the siren, used to warn the public of an impending raid, and the two cans have chemical closet fluid in them.

More Equipment Profiles to come.

PLEASE NOTE: NO EQUIPMENT IS KEPT IN BRANDSBY POST. ALL KIT IS REMOVED FROM THE POST WHEN NOT STAFFED. KIT CAN BE VIEWED IN THE POST BY PRIOR ARRANGEMENT.