The charcoal burners that feature in the Swallows and Amazons series are father and son, Old Billy and Young Billy (the Billies). They work in the traditional Cumbrian industry, charcoal burning, where they burn wood very slowly, under a mound of turf, in order to produce charcoal. They have quite a nomadic existence, living in a hut in the woods, making sure the fire remains covered throughout the night, and moving to different sites around the Lake. Camp Might Have Been in Pigeon Post (on the edge of High Topps) is a former charcoal burners' camp.
In Swallows and Amazons the Billies are working in the woods on the eastern shore of the Lake, a little to the south of Wild Cat Island. They see the charcoal burners at night (SA12), visit them the next day in their hut, which is a Red Indian wigwam according to Titty, and see Young Billy's adder (SA13). Old Billy says that my dad .... was burning on these fells a hundred years ago, and recalls a visit from Mrs Blackett, then little Miss Turner. Young Billy warns them of talk in the Bigland pub about what is in Uncle Jim's houseboat, which John promises to pass on.
In Swallowdale Mrs Jackson tells them that the charcoal-burners were not working on this side of the lake but up beyond the moor on the other side, in the next valley (SD2). They have moved to Heald Wood some way to the west of the lake. The two much younger natives, Bob and Jack (Mary Swainson's woodman), take Titty back on the horse-drawn log to Swainson's farm (SD30). Young Billy looks after Roger for the night in their hut (wigwam) after he sprains his ankle (SD31).
Old Billy is at a hound-trail over Bigland way. He had heard that Jim Postlethwaite would be there thinking he would be the oldest, but Jim was nobbut eighty-nine and Old Billy had seen ninety-four this last back-end (SD30).
Young Billy himself was over seventy and had grandchildren much older than the able-seaman, but she was more out of breath than he was as they climbed up the wood. When Titty reminds him she must get back to Roger, he says I'll be thinking I'm getting old next. He mentions the Blackett lasses, and says that with old Miss Turner staying at Beckfoot they won't be seeing so much of the lasses (SD30).
In Pigeon Post, the Billies are away at the low end of the lake (PP7). The Plunk ... plunk noise of John's axe and the rhythmic scrawk of Nancy's saw reminds Titty of the charcoal-burners (PP27), and Peggy says that the charcoal-burners keep their mounds burning for weeks and weeks (PP28).
There has been a resurgence of charcoal burning in the UK in recent years with organisations such as Bulworthy Project making charcoal and running charcoal making courses.