Simplify the following text for a Grade 12 native English-speaking person.
Original: The main voluntary ambulance providers are the British Red Cross and St. John Ambulance , which have been providing emergency medical cover in the UK for many years , including active service in both World Wars ( pre-dating the existence of any government organised service ) , and along with St Andrews Ambulance ( now St Andrews First Aid , which no longer provides an ambulance service ) ran statutory ambulance services in the United Kingdom under contract to the government until a reorganisation in 1974 . The primary activity of both organizations in relation to ambulances , is the provision of covers at events as an extension of their first aid contract .
Simplified: The main activity of the organizations apart from training and education , is providing ambulance cover at events , as an extension of their First aid contract .