Andrea got almost everything right.
The name Folgore was given to the top of the line racing bike in the 30's. It may surprise many to know that the Folgore was not however the most expensive bike in the Bianchi range, that honour goes to one of the roadster models. The Folgore was supplanted as top racing model by the Folgorissimo in 1949, which was a very short-lived name as this is the model that Fausto Coppi rode to victory in the Paris Roubaix in 1950. It therefore was immediately, less than one month after the victory, renamed as Paris-Roubaix (in French, not the Italian Parigi-Roubaix). Likewise the one-lever seat-stay mounted derailleur also changed name to Campagnolo Paris-Roubaix. The Tour de France was indeed in response to Coppi's Tour win. The model ran concurrently with the Paris-Roubaix model with the main difference being the derailleur. The sales of the Paris-Roubaix model were short-lived and it was dropped quite quickly. Then the Campione del Mondo model followed Fausto's World championship in Switzerland. Later it was renamed Specialissima when Coppi started riding Coppi branded bikes.