Although rather smaller than the rest of Penguin’s clothbound classics collection  (about 10 cm x 17 cm), and made of a finer weave linen cloth binding, the mostly philosophical non-fiction titles included in the original Pocket Pocket Hardback Classics collection (selected because they have “changed the history of thought”) may be considered a very closely related series.

The first 10 titles in this series were released in 2014 , with two more following in 2015, featuring two toned covers, including matt foil decorations by the ever-talented Coralie Bickford-Smith stamped onto the binding. The text block is glued (not sewn) but the pages are acid-free and they include coloured endpapers, head & tail bands, and a bound-in ribbon bookmark. The cover designs featured geometric patterns, intended to be symbolic of the nature of the texts as timeless pieces of literature.