Originally Posted by
Dannyboy21
I kept digging after posting the question because I can't let things go. In the digging I searched instead for pictures of the 80s models. Of course I found a dbl triangle that looked a lot more like the bike in question below. And of course the pic is non drive side. Seller says derailleur says brev campagnolo. I told seller to send me pics and I would arrange the purchase. He told me to hold on. Oh vey. Caveat emptor. This is my short answer.
The pictured bicycle is the mixte version of the TdC manufactured by Procycle in the early 1980s. The spec derailleurs were an unspecified SunTour model but in the literature they look like a low end model, possibly Honor/Spirt. Despite the non-drive image, your picture clearly shows SunTour Power Shifters which at least corroborates SunTour derailleurs. The frame is hi-tensile steel.
The other possibility is that the seller has mistaken a CCM Concorde for a TdC. Both came in similar colours (slightly different shades of purple) and the Concorde did use Reynolds 531, though it was only plain gauge and only in the main triangle. The Concorde was available in a mixte frame. I could see someone who is not knowledgeable about bicycles confusing the two tubesets and not picking up on other differences. While the Concorde was never offered with Campagnolo components, its not inconceivable that the OEM Simplex Prestige were replaced by an entry Campagnolo model, such a Valentino.