Bounding Box with a Single Layer

POST http://<hostname>:<port>/rest/Spatial/MappingService/maps/image.png;w=400;h=400;b=-140012,3087,736671,1193876,epsg%3A27700
Content-type: application/json
Authorization: <Basic or Spectrum Token>

{
   "layers":[
      {
         "type":"NamedLayer",
         "name":"/Samples/NamedLayers/UK_REGNS_Layer"
      }
   ]
}