Last week I saw this in the U-District. It’s a Raleigh Twenty, I think late 1960s. After the success of Alex Moulton’s small-wheeled Moulton Standard, Raleigh decided to jump on the trend for small wheels and non-traditional frame configurations. However the Raleigh Twenty lacked the Moulton’s remarkable suspension system, and in using large volume, low pressure tires to compensate for ride comfort, the Twenty was considerably less spry. It was however cheaper.
This Twenty is a folder, though I believe some Twenties were not.