On sifting through some back numbers of Le Cycle - the French semi-trade semi-sport magazine, I chanced to find an announcment in the March 1977 edition,f rom MERCIER, about the firm's intention to launch its Prestige range.
The article states that all frames made under this banner will be custom-made, entirely by hand, to individual order with no more than 200 being produced each month. Apparently each frame was presented in its own gift case..and each carried a special number..but the article did not say whereabouts on the frame. Frames were made either of Reynolds 531DB or of 753.
To contrast with these frames I have posted on my Flickr site :-