The Dawes Kingpin did indeed look similar, but it was not the same design.



When you compare the design of the Twenty, and the Kingpin, with many of the 'modern' folders that became common in the last decade, it is clear that the Twenty was an extremely influential design. Look at the Downtube 8H, for example:



That one's not mine, but I commute on one of these during the summer (I take it on the Long Island Rail Road). Mine is heavily modified, with fenders, lights, etc; but its Raleigh heritage is still obvious.

Important differences:

1. The frame hinge of the Twenty is centered on the frame tubes, which makes for a strong frame but a poor fold. In contrast, the Kingpin has an offset hinge, like most other European folding bikes of the 60s-70s, which makes for a better fold but an inherently weak mechanism. European U-framed folders often fail at the hinge. Nonetheless the Downtube (and other modern folders) have the offset hinge, though substantially beefier than what you'd find on European folders of the 70's.

2. The long seat tube of the Twenty makes the folded package too big; by lowering that, and making the seat post longer, modern versions fold up smaller.

3. The long head tube of the Twenty and Kingpin has that same problem; and to fold, they only turn the handlebar sideways and lower it a bit. Modern versions have a shorter head tube. Furthermore, modern versions have the handlebar attached to a "handlepost" that folds, rather than turns; it is typically hinged at a 45 degree angle, so in folding the handlebar turns parallel to the frame and drops down, virtually disappearing. Again, this makes for a much more compact fold.