There is Morse code etched into the glass walls of Diane Taverner's office. When read from outside her office, it seems to read "Defend Regnum." This could be interpreted as "protect the kingdom."
"Upshott Flying Club" is actually Brimpton Airfield just outside Reading, Berkshire. The name can be seen faintly painted onto the roof of the clubhouse (along with the airfield's radio frequency) as River first arrives.