This series was the main correspondence series for the Embassy from 1954-1957 for all matters except those classified secret or above.  
Amongst the subject areas covered by the files are:
 
     political intelligence;
     trade matters;
     United Nations and other international bodies; and
     visits by VIPs to the United States and Australia.
 
The files have a year(s) stamped on the cover and this stamp(s) may have been added after the files were raised as the stamp(s) give the date range of each file.
 
This could be to assist staff to distinguish between files from different series with the same numbers or titles. However, the multiple number system is the primary control.