I have the same exact bike, a 68-69 green anniversary super course with the anniversary badge (and some rust.) At the seat lug, one of the stays has begun to crack, and the line traveled over to the vent hole, and has luckily stopped.
The 'Super Course' is one of the only models made by Carlton that had the same names for both the U.K. and the USA models, in many years. In general, the Super Course was a 531 plain-gauge main-tubes bike on both sides of the Atlantic. Other models, were renamed (i.e. Giro D'Italia = Raleigh Pro 71-76, International = Franco Suisse, etc.) There was a late 60's model with a fastback seat cluster that didn't make it to the USA (but did make it to Australia ...)
The Gran Sport and below used a straight serial-number sequence, stamped on the rear stays, even the ones that were made in Worksop. If you look at Raleigh badges ALL badges say Nottingham, England. Some Grand Prix's have a decal that says, "Made by Gazelle of Holland" and some Grand Prix's have a 'Carlton, Race-Proved' decal which I presume means it was made by Carlton.
The problem with Nervex lugs is that they were stamped and welded and for whatever reason, they came out with a lot of shoreline defects. The high-end makers had to put a lot of work into these lugs to clean them up and get them looking good, especially before chroming. That's why the Schwinn Paramount was so expensive and that's why the Raleigh Internationals generally are poorly finished (as a low-cost model, there was no money for such labors of lug :-) :-).)
- Don Gillies
San Diego, CA