This class comprises of Headquarters case files that came to light after the appropriate class catalogues (POST 30, POST 31, POST 32, POST 33, POST 102 and POST 122) had been completed. It includes files found in the registry repository in the former Headquarters at St Martin's le Grand, which were filed upon completion and then forgotten. It also includes papers which remained with the originating Headquarters departments until the Headquarters moved in 1984. The majority of these are accumulations of files on a common subject spanning several years.
The manner in which this class accumulated means that it covers a wide range of subjects, ranging from allowances for keeping horses (POST 121/159) and cats (POST 121/22) to the Post Office's official attitude to divorce (POST 121/341). There are also a few appointment papers (POST 121/340, POST 121/344, POST 121/352, POST 121/430, and POST 121/431).
No further information available