Wondering about a house I am thinking of buying. It has chimney
breasts which take up room space downstairs aswell as upstairs in
bedrooms. If I could remove the chimney breasts it would increase
space.

On the roof the chimney has already been removed. in the Attic the
chimney curves down splits into two sections like in the shape of a
gothic arch, this then goes down through the house.

Would party-wall permission be needed? How about if I'm a quiet
worker...no-one need know! I'm very certain next door does not share
this chimney, because their stairs would be along this wall just as
the stairs in this house are also along the other wall - with no
fireplaces.

Is it simply a question of starting at the top in the attic, and
removing it brick by brick? Then clean & point what is inside the
chimney, then render and patch up the ceilings.

Cheers