- There had been some apocalyptic event and now everyone was scared of machinery and electricity.
- A romany family was (or may have been) involved in some way. A girl with long red/brown hair, maybe.
- I distinctly remember her being terrified to walk under electricity pylons and them making some weird humming noise that only she could hear.
Not much to go on, I know, but if this rings a bell to anyone, I would love to track down and read the book. I may be mixing up more than one story/drama/programme/book, I guess…
ETA links from the comments:
The trilogy - and the TV series - is called The Changes by Peter Dickinson.