Thanks for all your comments. Looks like reprinting is a favourite option, which is less disruptive than a new staircase and a repainted will not destroy our current wallpaper which will be ripped if we fit a new staircase and the paper is no longer available. i attach a better photo of the colour of the wallpaper (it's a gold colour) so that you can help me select best colour. I really don't want white. we plan to replace the doors to a light oak with glass inserts to help lightened the hall and lay cream tiles on the floor. we will probably replace the carpet on the stairs with a similar patterned one

Yes fill the void with insulation and breathable membrane and clad over the top can you for see any issues with doing that

Hi Macca, The top of newel is not structural and very straight forward to replace. There are even newel post replacement kits. The process is very easy and very diy-able even if you don't use the kit. If you have some basic wood working skills as long as you have enough of the two bits of wood overlapping you can use any joint you have the skill to make even a basic lap joint. Kit is obviously quicker https://www.youtube.com/watch?v=yN4fco0shLs https://www.youtube.com/watch?v=kxn3X8Nsyz0 Another approach is to clad the newel in new wood. You are esentially building a new post on top of the old one. https://www.youtube.com/watch?v=npflGAuaSzQ Or finally just sand it down fill out the damaged areas with filler or epoxy and then repaint https://www.youtube.com/watch?v=7dAjvRyYi0E Regarding the string then yes as long as its sound and not damaged e.g. termite or rot.

I wonder if the creaking is from the threads rubbing against the risers? I had a bit of creaking in mine and used a bit of calk in the joins and it seemed to have alleviated that issue. Appreciate that your staircase is older but it is worth a try. (I used paintable calk)