Not sure what you are concerned about, the offset in the wall will give it some stability and as others say the first floor joists/floor will provide lateral stability.
The guidance to the regs on structure (google 'Approved Document A') recommends that laterally-unsupported walls are no longer than 12m between intersecting walls.
In your case, I would guess the floor joists are probably running left-to-right, and these will provide some lateral restraint to the wall in the vertical plane. Additionally, you have a buttress in the form of the chimney.
Why are you concerned about this wall?
The guidance to the regs on structure (google 'Approved Document A') recommends that laterally-unsupported walls are no longer than 12m between intersecting walls.
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