This is the Corgi 406/9 Mercedes Bonna ambulance I picked up off ebay for a decent price. This is in the Swiss livery. There are about 10 varieties of these cars. The rest of the series I have can be seen here:

406 Orange livery

406/1 German issue

407 Blue livery

91775 St. Bartholomew's Hospital

Red Cross Issue

Norwegian Issue

London Issue