E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
The bank or bench was the counter on which shopkeepers of yore displayed their goods. Street vendors used to mount on their bank to patter to the public. The French word is saltim banque; and the Italian word Cantambanco (i.e. canta in banco, one who patters from his bank).
In Italian, montambanco (a quack-doctor) is also in use.
Se disant estre quelque trabe, on quelque Juif convert, il se feignoit medecin du roi de Perse, et comme tel il montoit la banque. Cestoit là que, pour debiter ses drogues, il étourdissoit de son babil toute lassemblée.Histoire Generale des Larrons, book i. chap. xxix.
There were temporary mountebanks as well as more regular merchants. In Attica, the names of Dolon and Susarion of Icaria are distinguished. In France, Tabaria, Tabarin, Turlupin, Gauthier-Garguille, Gros-Guillaume, Guillot-Gorju, Bobêhe, Galimaufré, and Gringalet (a marvellous number of Gs). In England, Andrew Borde, and some few others of inferior note.