The world Christopher Chant visits with Tacroy in The Lives of Christopher Chant is bleak and stony, with rolls of moorland under a heavy grey sky. They visit a bleak stone farm halfway up a hill, where they are met by a group of thick-armed taciturn women whose breath smells strongly of garlic, nearly drowning out the strange coppery odour of the parcels they give to Christopher and Tacroy. The people in this world drink bitter malty tea.
There are dragons in Series Eight, whose blood is a highly-prized, not to mention insanely dangerous - and for both these reasons, strictly controlled - magical ingredient.
The world called [Home Eight]? in the non-Chrestomanci series story "Dragon Reserve, Home Eight" is similar in geography to Series Eight, and also has dragons (in addition to being part of a world series similar to those of the Related Worlds). This is not entirely a coincidence, as Diana Wynne Jones wrote "Dragon Reserve, Home Eight" shortly before The Lives of Christopher Chant while she was working out the details of the Related Worlds.