Complex sentence: A storage alcove ran off the one end of the pantry under what was the smallest of winding stairs just 46cm wide and at the back end, brick steps ran up to the rear door, the back yard being at a higher level than the front.
Split into simpler sentences: A storage alcove ran off the one end of the pantry under what was the smallest of winding stairs, just 46cm wide and at the back end. Brick steps ran up to the rear door as the back yard was at a higher level than the front.