It’s the ground floor of a protected staircase and shows the door swing directly over the bottom of the stair within the landing space. This is to protect those on the staircase as there's a danger of being hit by the door swinging into them when they’re nearing the bottom of the steps or an injury caused by a fall.

A1) If the door swings away from the stair and opens into the room there is no risk of collision with the door and people using the stair then the 400mm would not apply, if the door opens towards the stair, then the 400mm applies. The 400mm allowance for dwellings is because there is usually only one person on the stair so they could stop to steady themselves to ‘dodge’ the door swinging at them. While the area around the door in the image above needed a replastering job and redecoration, the door and frame could be reversed to open away from the stairs and into the lobby instead, because the number of people moving from that area was less than 60. Further information Our range of dolly trollies and pallet dollies are made from the highest quality of materials. You can put your trust in a moving trolley from BiGDUG because they’re durable, reliable and can withstand a large amount of weight. Move pallets with ease Clear space should be provided at the top and bottom of flights of stairs measuring at least the width of the stair and this can be reduced to 400mm at the bottom of stairs within dwellings.Q2) a door frame in line with the base of the stairs in which the door swings away from the stairway ( which is what this question was asking you) Part K does not cite either of these 2 scenarios. I would imagine this must be a certain distance because a door up against the foot of the stairs would seem an obstruction even if it opened away from the stairs - which it would have to anyway?”