For just a few years Raleigh outfitted the Roadsters with 8” crank arms, and this appears to be one of those. Christopher has run that version on the Tour for a few seasons. Around 1970, or 1971, they went back to the 7” version, and used those until the end.
The 8” version is tough to source, be most careful taking that crankset apart. I would add the 8” crankset is, in my opinion, a young guy thing on a ride like the Tour. But, people told me the same thing about showing up on a Roadster, without thought to the crankset, the few times I did it.
Ted