The landing work continues. I've had to use various shims on the studs to flatten out the wall prior to plasterboarding it. The studs are all over the place and the shims have been anywhere between thin cardboard and 8mm of plywood. The problem is a combination of the wood shrinking over the last 120ish years, and the original Victorian carpenter throwing up the studs any old how and leaving it to the plasterer to level it all out. It would have been quicker for me to take down the entire wall and rebuild with new wood. However... that would involved too much damage to the ceiling in the bedroom and end up costing more and would have put that room beyond use for too long.