Jim O'C posted:So, it is entirely possible it was cheaper for both companies to buy passenger coach shells from Bing and adorn them at the factory before assembly.
Not if I understand you correctly. If a coach is lithographed, the printing takes place on a blank sheet of metal, then the sheet is punched and formed into the shape and size required. In effect, it is decorated/adorned before it is formed, so what you are suggesting could not happen.