The cache is NOT inside the bunker and no attempt should be made to enter it.
Since its inception in 1925 as in integral part of the UK air defence system, the primary role of the Royal Observer Corps (ROC) was the recognition and identification of hostile aircraft. With the start of the cold war and the increasing threat of nuclear attack in the 1950's, the ROC was given the added responsibility of reporting nuclear bursts and monitoring fall-out which necessitated the construction of 1,563 underground monitoring posts throughout Great Britain & Northern Ireland. On the 15th June 1955 it was announced in the House of Commons that `steps are being taken for the ROC to give warning of and to measure radioactivity in the event of air attacks in a future war.’
Regular training continued through the 70's and 80's but in 1991 it was decided by the Home Office & MOD that the ROC would cease active training and the remaining underground posts were closed at the end of September that year. This underground monitoring post in Middleton Stoney was opened in June 1959 and was in use until it closed in September 1991.
You are looking for a small Tupperware container.
This is a fascinating subject and for those of you who might agree, further information can be found at 'Royal Observer Corps'
You may also like to visit the following bunker themed caches :-
"Cold War Cache" by mailboxmonty or
" Cold War Berkshire - Crowthorne's Nuclear " by AmayaTom