There is something strange going on here. The Linux kernel has the ntfs driver builtin, and configured to allow writes when ntfs partitions are mounted.
Except that we can't. Get an error when try to write. It used to work, something has changed.
Anyway, writing to an ntfs filesystem is supposed to be less reliable using the kernel driver, and ntfs-3g fuse-based driver is preferred.
I didn't have ntfs-3g in the initramfs as compiled statically it is about 410KB. Have now put it in and modified the 'init' script to use it.
This is a good thing, as writing to ntfs filesystems will now be more reliable. Though, it may be possible to avoid writing from the initramfs, and remount with ntfs-3g when running in the main Quirky f.s.
The downside of ntfs-3g is that being fuse-based, it is slow.