I'm planning to replace my newel and handrail at some point this year and I've been having a look at the construction but I'm a bit puzzled about the bottom. It's a 70s build and put in to do the job rather than to look nice. I'm almost certain that the stringer is joined to the newel by a tenon joint and secured with three nails. The newel sits on the floorboard and definitely doesn't go through. Riser 2 and tread 2 look to be rebated into the inside face of the newel. Where I'm uncertain is how the bull nosed tread 1 was fitted. It seems to me that the stairs were constructed from tread 2 upwards and the first step added on afterwards. Can anyone confirm my tentative investigations, or even point me to a typical set of diagrams?