I do not consider myself an expert but the Military Motorcycle buffs did a full run down on that photo quite some time ago
As they are nutters for detail they identified publicatin date, publication title , photo date, time , location, group and bike including the date of manufacture .
Lots of young women at the time looked very similar to the princess , just the same as when Di married Chuck the "Dianna " suddenly became the worlds most popular hair do .
If you feel like it there are thousands of QEII tribute documentries done by real journalist available on the web that went through her military time in great detail
From memory she drove an ambulance which was a fitting job for a humble Princess dedicated to the service of the people .