You are moving to or from a flat above the ground floor.
The width is not the constraint
A Victorian domestic staircase rises to a half-landing, turns back on itself, and rises again. At that turn the usable space is not the width of the flight — it is the diagonal a long object can describe while pivoting.
That diagonal is what defeats wardrobes, sofas and mattresses, and it is nearly always tighter than both the front door and the stair itself.
- Measure the width of the half-landing from the wall to the banister.
- Measure the ceiling height directly above the turn — this is what stops tall items tipping.
- Measure the depth of the landing from the top step to the wall opposite.
- Photograph the turn from below and from above.
Later handrails make it worse
A great many Ealing conversions had a handrail added to the communal stair when the house was split, for building-regulations reasons. It is usually fixed to the open side, and it takes a surprising amount out of the turn.
If your stair has an original banister on one side and a newer rail on the other, measure between them rather than to the wall.
The newel post is what actually catches
Not the wall. The newel — the thick post at the bottom and at the turn — projects further into the space than anything else and is at exactly the height a sofa arm meets it.
It is also frequently the original joinery, and marking it is the kind of damage a freeholder notices.
What to do with a piece that will not pass
Three options, in order of preference. Take it apart and rebuild it in the room — most Victorian and a good deal of modern furniture is designed to. Take it through a window with a hoist, which on an unmanaged conversion needs the freeholder’s agreement because the hoist stands on shared ground. Or accept that it stays.
All three are fine. What is not fine is finding out on the day, with the stair blocked and two other households trying to get past.