How do I remove lining paper that's had oil eggshell paint on it for 25yrs?

By scarifying and steaming you are doing what’s necessary to get it off and as long as the steam is penetrating the paint and paper back to the plaster I don’t see what else you can do. It’s a time consuming filthy job I know from experience but it’s so worth it in the end.

Maybe try using a blade and make horizontal or diagonal slits in the paper and then leave the steamer running in the area with the doors closed for an hour or so? I’m not sure where I know this from but it’s ringing a bell in the back of my head somewhere!

I think you can buy a wallpaper scorer which will do that, or is that what you have already (a scarifier?), then soak or steam the paper, then scrape.

It sounds like a long job unfortunately.

How about, (if you're up to it) coating a test patch of Nitromores (?sp) on it?

Leave it to soak in, and I think that will bubble up the paint.

It's scary stuff though.

You could try a wallpaper stripping solution. www.wilko.com/en-uk/wilko-500ml-concentrated-wallpaper-stripper/p/0157037

My OH had to strip off some multi painted wood chip paper recently, he did find that using wallpaper stripper (called Everbuild) on it (after scoring the surface well) and then leaving it for at least half an hour, reapply then leave for another soak made the job much easier. He thinks he applied/soaked it three times before attempting to strip the paper. Found it to be very good. He bought his from Toolstation £2.34 a bottle. Code number 59051

Think i would hire someone to do it for me, can't abide wall paper stripping!!!

The first thing that came to mind was.....With great difficulty!

The scarifier is a tool with spiked wheels that tears the surface of the wallpaper all over. This alone is nowhere near enough. I've just read that you can sand the surface with the toughest sandpaper to remove the waterproof seal. I shall try this & then scarify & steam. I'll report back how it goes.

Make sure you wear a mask, Mary
(Sorry if that is telling granny the obvious)

It sounds a heck of a job!

I can report back that the sanding worked! Once the surface was sanded the paper came off much more easily.