Square-al Staircase (as the client, John Roseveare, called it).
The beauty of making composite structures.
A wobbly bit of steel and a stack of gluelam blocks as treads, combine to become a solid staircase in a narrow space.
Less than 100mm openings in the tread rises, mean that no additional downstands or infills are needed to meet safety regulations. Glass balustrade panels were later fitted.