Context: In 1998, the Saudi crown prince Abdullah visited the UK, the Queen offered him a tour of their Scottish estate in a car. Expecting some attendant to do the driving, the prince was shocked when Queen Elizabeth herself got into the drivers seat and drove off.
This was shocking for the prince because at the time it was illegal for women to drive in Saudi Arabia and here the monarch of the UK herself was doing so just to taunt him.
Queen Elizabeth herself used to be a driver and mechanic during World War 2 and as such was quite qualified to drive by herself.
She drove the fixed vehicles. She was a delivery driver rather than an ambulance driver. Ambulances go where there are injured, which is where the danger is. No way she would be allowed near that.
Ah makes sense. The article didn't say that she drove ambulances specifically. Edited the post.