The stairway is one of those nice things which look more difficult than they really are. First the concertina-folded steps are attached to the inner leaf of the outer stringer.
Then the inner stringer in two layers and the outer layer of the stringer and handrail.
This photo also tells you why I chose to use K502 as my model - how could I resist "Mazawattee Tea"?
The only slightly awkward stage is adding the under lining for the steps and stringers. It needs a little careful trimming to leave a neat bottom edge, though fortunately this does not show too glaringly once the stairs are in position.
And here they are:
