Everything has been pulled except for the cranks, BB, and HS. The seat pin measures 26.8, but I'm not sure that measurement has any real meaning because the unusual milled seat tube "collar" effectively shims things down. Essentially, the seat tube is something larger in opening diameter than 26.8. With the Mafac Competition calipers and the 27" wheel set in place, the frame was clearly designed for that size: there is absolutely no additional adjustment left in those arms to reach a 700c wheel. The copper "head badge" lifted off easily; there are no holes underneath, so the probability increases that there was no original head badge. The rear is spaced for a five speed - no surprise there.
Going back and checking dates for the mixed bag of components yields some further speculation: With the exception of the RD, pretty much everything else dates from early to mid-70's. It's a pretty good guess that this frame was at least built up in the mid-70's, and likely built at that time also. The RD is more consistent with the mid-90's so I'm guessing it got replaced along the way. Not unusual.
No serial number located at this stage, but I'll keep looking. I'll likely go ahead and strip the color, which is absolutely toast, check for any rust, and then respray it. That won't get started until I dig up another Stronglight puller. I loaned out several tools about two years ago and never got them back, never heard from the guy again either. No good deed ever goes unpunished...