I did say things would slow down a lot after my son was born. We haven't however been
that slow.
The wall above the stairs was originally covered with a plastic coated ply board. This was very common around here 40 years ago as it was a way of very cheaply and quickly covering unsightly walls, and give it that wooden walls effect that was very popular at the time.
Underneath we found small holes in the walls from the nails, construction glue used in conjunction with the nails to hold the panels up. So we stripped the wall paper back to the plaster, patched the plaster up, and then skimmed the whole wall. I have to say, I'm very pleased with the results: