On 26 Mar, 17:23, chudford wrote:

Is there any way that they can be stripped back to the original wood
surface in situ without wrecking the surrounding ceiling?

Start simple - try samples with Nitromors, or with heat stripping. You
might be lucky and it might just work.

Best thing I've used for this is a Makita brush sander (like a 6" wide
rotary drum brush, made of sandpaper). 500 quid, but yoiu can hire
them.

Much depends on what they're covered with. Bituminous stuff is
horrible and I'd think seriously about either leaving them alone, or
having a gritblaster come in and do them for me.