St. John Ambulance Service MedalSt. John Ambulance Service Medal Full size medal Unmounted with 15cm ribbon as required for swing mounting. Miniature size medal Unmounted with 10cm ribbon as required for swing mounting. The Service Medal of the Order of St John is awarded to recognise both conspicuous and long service with the Venerable Order of St John, particularly in St John Ambulance,[2] both in the United Kingdom and in a number of other Commonwealth countries. In the United