Complex sentence: His insistence on attention to detail saw the improvement of many attitudes and methods at the Ordnance Survey, his planning saw the production of many of maps now viewed as pinnacles in the classic period of map making.
Split into simpler sentences: His insistence on attention to detail saw the improvement of many attitudes and methods at the Ordnance Survey. Close's planning saw the production of many maps now viewed as pinnacles in the classic period of map making.