These are pretty early Raleigh 20s. I have a 1971-72 model with 1971 rear hub code.
Tony Hadland's Raleigh book indicates that the Twenty line (which initially was a non-folding small-wheel bike) first appeared in general in July 1968, but that the Twenty was "soft launched" such that few people were made aware of it. The Twenty appeared in Canada in 1969, but that 1970 was a key year in the marketing of the bikes in Britain and the US. By October 1970, the full array of varieties of Twenty were fleshed out. 1970-71 folding Twentys are early models. Mine is basically the same as the ones you've found and it's a 1971-72 model.
The 1970 catalog picture may show an early variation or experiment with the folding frame - the picture wa likely taken very early in the life of the Twenty folder such that the final production version was completed only after that catalog shot was taken.
It's funny that the Twenty was "soft launched" such that it seemed there was not a great deal of confidence in the bike initially. It turns out the Twenty was one of the greatest of the old generation of folding and small wheel bikes. A survey of consumers in the mid-1970s placed the Twenty firmly in first place for small wheeled bikes, ahead of the rival Dawes Kingpin.
The Twenty gets its "feel" largely from the presence of a plastic bushing in the top of head set. This bushing is prone to cracking and breaking and should be handled with care. The bushing is there to "dampen" the steering so that the bike feels more like a full-sized bike (small wheel bikes can have a light "snappy" steering that takes getting used to compared to a regular bike; the bushing was Raleigh's solution to this).
The redline tires are the original ones for this era. They're pretty well-made: my Twenty is still running its original tires and tubes, which is an accomplishment after 47 years. The redline tires in good condition have become somewhat valuable on their own because the muscle bike and BMX guys like them.
The Twenty frame is very robust for an old-era folding bike. The bike does not fold up as neatly as a modern folder but, it's still an excellent bike. The Twenty is when Raleigh finally got the small wheel bike "right". Raleigh had problems with licensing the Moulton designs before this, and the Raleigh Small Wheel bike was generally too small (and the tires to slow-running and soft) for a full-sized, adult rider.
