Complex sentence: On a walk with friends, Armstrong was struck by the attractiveness of the site for a house and, returning to Newcastle, he arranged for the purchase of a small parcel of land and decided to build a modest house on the side of a moorland crag.
Split into simpler sentences: On a walk with friends, Armstrong was struck by the attractiveness of the site for a house. Returning to Newcastle, he bought a small parcel of land and decided to build a modest house on the side of a moorland crag.