Jerry,
I heavily suspect that the Mark I was a Carlton Flyer model, as it would be totally sensible for Carlton to put forth its top-of-the-line model as the top-of-the-line Raleigh Professional in 1968/69. Can you please compare your Mark I to my 151 bcd 1967 Carlton Flyer (see jpg below)?? I can send you geometry and other measurements if you need further details :
http://www.ece.ubc.ca/
(that bike is a "challenge restoration" project-bike of mine.)
I suspect that perhaps that as the Giro D'Italia model in the U.K. started to experience more sales, and/or because Raleigh was offering 2 seemingly identical bikes (Pro, International) in 1968-70, they might have gone the other direction and offered a Pro bike that was gaining popularity in the U.K. and was different in every way (Giro D'Italia) from the International - fastback seat cluster, steeper angles, lighter fork, sloping fork crown, italian (not nervex) lugs, etc.
Could the Mark II and Mark III owners please send me an email with your bike year and size ?? I'd like to poll the owners with the purpose of measuring and determining what changes (if any) happened in going from the Mark II to the Mark III and to the Mark IV models.
- Don Gillies
San Diego, CA, USA