County, based in the Midlands, operates according to Pre-Hospital Trauma Life Support (PHTLS), which a Royal College of Surgeons (England) course.
Basically, emphasis is on "platinum 10 minutes" on scene in a "time critical" patient (ie. one with serious injuries) - only actions on scene being securing of the airway (if necessary) and spinal immobilisation. Then continue rest of treatment en route to hospital - drips, intravenous fluids, analgesia, immobilising factures, etc.
Based on evidence from Sheffield University showing a higher risk of dying the longer that is spent on-scene.
Anton