Sadly in Britain, air ambulances are charities and rely on donations from the public to keep running.

Air ambulances are about bringing an A&E department to the patient if they don't have time to get there. The pilot needs to find an appropriate landing site - make sure it is big enough, identify hazards that may prevent landing safely. They don't always show on Flight Radar to protect patients.

my parents got married there ❤️

St. Thomas' isn't a major trauma centre which is probably why an air ambulance was dispatched.