Complex sentence: Although the station is north of Welwyn Garden City, the village of Welwyn is about west in the modern district of Digswell, which in 1865 was known as High Welwyn and is shown on maps of that period.
Split into simpler sentences: Although the station is north of Welwyn Garden City, there is the actual village of Welwyn about west. Furthermore, the station is actually located in the modern district of Digswell, this area was, in 1865, known as High Welwyn and is thus shown on maps of that period.