This series was the main correspondence series for the Embassy from 1952-1953 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 VIP's 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 number of title.  
However, the multiple number system is the primary control.