INFORMATION:

Communal : is usually the mess's, sergeants, officers and the men's institute. In earlier communal sites the WAAF's had their own parallel site with mess's, etc and sleeping accommodation. On later sites the WAAF often used the same facilities as the men but always slept in their own WAAF site.
Sites 1 -4 : were for sleeping, ablutions, etc.

Above : the communal site within the yellow square.