Removing the stair carpet
The plan is to sand down, and then lacquer the staircase. However, the stairs up to the “tower” are also carpeted. So, sort of as a trial run for the tower itself, I took on the stairs.
I got lucky: the carpet is every bit as cheap and nasty as it looked. So, where it wasn’t already lose it was just a question of cutting through with a carpet knife and peeling it away from the underside. This could then be fairly easily scraped and then swept away.

Except for the very top of the stairs, which has an additional layer of what looks like artificial grass on underneath, and where the glue hasn’t dried out quite as much, making it harder to remove.

You can also see that the quality of the wood on these steps isn’t quite as good as lower down the stairs.