I have been noting some of the short card tour guides that were produced for sites in State Guardianship, e.g. Caerphilly Castle, Criccieth Castle. One was produced by the MPBW for Caernarvon (Caernarfon) Castle in 1969 (price, 6d). This has a tour of the castle with 13 key points.
The same plan appears inside the card back cover of Alan Phillips 1961 souvenir guide of the castle. It also contained some of the line drawings of the features that reappear in the 1969 guide. However there are some differences in the text, and the card seems to use the revised text of the 1963 souvenir guide.
The text appears in the 1970 reprint but without the line drawings.
The back of the card guide has a short history of the castle.