The Amazons' red caps

"Swallows and Amazons" (1974)

In the classic series of children's books by Arthur Ransome that began in 1930 with the eponymous Swallows and Amazons, the Blackett sisters usually wear distinctive red knitted caps.  The caps aren't described much, only that they are knitted and that the red color can be seen for miles, as when the four Walker children aboard their beloved "Swallow" can easily recognize "Amazon" as she tacks across the lake, by the red caps of her crew.

"Swallows and Amazons" (2016). Peggy has somehow got hold of a striped cap here, instead of the usual red one.

Because Ransome was so vague about the style of cap that Nancy and Peggy wear, we have more leeway in choosing a pattern.  In 1920s England, a watch cap pattern would be a logical choice, and would certainly have been available to a knitting mother or grandmother who had a relative in the merchant marine or the Navy, who had knitted for servicemen during the recent War as so many women did, or who simply had sailors in the family, as do both the Walkers and the Blacketts.

"Crow's Nest Cap" pattern, probably from the 1910s, from "The Needle-Worker" magazine's booklet Comforts for Sailors, and How to Knit Them. Note that the cap is worked from the top down.

One could also get a bit more elaborate than a simple watch cap, as the costumers did for these two filmed versions -- the 1974 Blacketts wear a longer version more like a ski cap with pompom, while the 2016 Blacketts' caps look very like the voyageur style.